METHOD AND SYSTEM FOR PRION INACTIVATION

Abstract

A method is provided for inactivating prions and is particularly effective in inactivating prions on medical devices. An article having a quantity of prions thereon is placed into a sterilization chamber. Pressure in the sterilization chamber is lowered to a pressure below the vapor pressure of hydrogen peroxide and a solution of hydrogen peroxide is admitted into the sterilization chamber and placed into contact with the article to inactivate prions on the article.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a sterilization system according to the present invention;

FIG. 2 is a block diagram of a vaporizer and diffusion path of the sterilization system of FIG. 1;

FIG. 3 is a block diagram of an alternate embodiment of a sterilization system according to the present invention;

FIG. 3A is a block diagram of an alternative embodiment of a sterilization system according to the present invention.

FIG. 3B is a sectional view taken along lines 3B-3B of FIG. 3A;

FIG. 4 is a block diagram of an alternate embodiment of a sterilization system according to the present invention;

FIG. 5 is a block diagram of an alternate embodiment of a sterilization system according to the present invention;

FIG. 6 is a section view taken along lines 6-6 of FIG. 5;

FIG. 7 is a block diagram of an alternate embodiment of a sterilization system according to the present invention;

FIG. 8 is a section view taken along lines 8-8 of FIG. 7;

FIG. 9 is a block diagram of a sterilization system according to the present invention;

FIG. 10 is a cut-away view of an outlet condenser/vaporizer for use in the system of FIG. 9;

FIG. 11 is a cut-away view of an inlet condenser/vaporizer for use in the system of FIG. 9;

FIG. 12 is a perspective view of an alternative inlet condenser/vaporizer for use in the system of FIG. 9;

FIG. 13 is an exploded perspective view of the condenser/vaporizer of FIG. 12;

FIG. 14 is a section view taken along lines 14-14 of FIG. 12;

FIG. 14A is a close-up section view of the valve assembly shown in FIG. 14;

FIG. 15 is an exploded perspective view of a thermoelectric heat pump and rod assembly employed in the condenser/vaporizer of FIG. 12;

FIG. 16 is an alternative sterilization system according to the present invention;

FIG. 17 is an alternative sterilization system according to the present invention;

FIG. 18 is an alternative sterilization system according to the present invention;

FIG. 19 is an alternative sterilization system according to the present invention;

FIG. 20 is a perspective view of an alternative inlet condenser/vaporizer for use in the system of FIG. 9;

FIG. 21 is a valve block employed in the inlet condenser/vaporizer of FIG. 20;

FIG. 22 is a cut-away view of the valve block of FIG. 21 as employed in the inlet condenser/vaporizer of FIG. 20; and

FIG. 23 is a flow diagram for calculating the concentration of peroxide which condenses upon the load.

Claims

1. A method of inactivating prions comprising the steps of: placing an article having a quantity of prions thereon into a sterilization chamber;lowering pressure in the sterilization chamber to a pressure below the vapor pressure of hydrogen peroxide;admitting a solution comprising hydrogen peroxide into the sterilization chamber and contacting the article with hydrogen peroxide vapor; andinactivating prions in the chamber through contact between the prions and the hydrogen peroxide vapor.

2. A method according to claim 1 wherein the concentration of the hydrogen peroxide in the solution admitted into the chamber exceeds 70 percent.

3. A method according to claim 2 wherein the concentration of the hydrogen peroxide in the solution admitted into the chamber exceeds 75 percent.

4. A method according to claim 3 wherein the concentration of the hydrogen peroxide in the solution admitted into the chamber exceeds 80 percent.

5. A method according to claim 4 wherein the concentration of the hydrogen peroxide in the solution admitted into the chamber exceeds 85 percent.

6. A method according to claim 5 wherein the concentration of the hydrogen peroxide in the solution admitted into the chamber exceeds 90 percent.

7. A method according to claim 1 and wherein the temperature of the article during the step of contacting the article with hydrogen peroxide vapor exceeds 30 degrees Celsius.

8. A method according to claim 7 and wherein the temperature of the article during the step of contacting the article with hydrogen peroxide vapor exceeds 35 degrees Celsius.

9. A method according to claim 8 and wherein the temperature of the article during the step of contacting the article with hydrogen peroxide vapor exceeds 40 degrees Celsius.

10. A method according to claim 9 and wherein the temperature of the article during the step of contacting the article with hydrogen peroxide vapor exceeds 45 degrees Celsius.

11. A method according to claim 1 and further comprising exciting the hydrogen peroxide vapor into the plasma phase and contacting the prions with the hydrogen peroxide in the plasma phase.

12. A method according to claim 11 wherein the plasma density is at least 10 milliwatts/cm3.

13. A method according to claim 12 wherein the plasma density is at least 20 milliwatts/cm3.

14. A method according to claim 13 wherein the plasma density is at least 30 milliwatts/cm3.

15. A method according to claim 14 wherein the plasma density is at least 40 milliwatts/cm3.

16. A method according to claim 15 wherein the plasma density is at least 50 milliwatts/cm3.

17. A method according to claim 11 wherein the plasma is in contact with the prions for at least 2 minutes.

18. A method according to claim 17 wherein the plasma time is in contact with the prions for at least 3 minutes.

19. A method according to claim 18 wherein the plasma time is in contact with the prions for at least 4 minutes.

20. A method according to claim 11 and wherein the plasma is generated between an anode and a cathode and wherein a gap therebetween is less than 0.6 inches.

21. A method according to claim 20 wherein the gap is 0.5 inches or less.

22. A method according to claim 20 wherein the gap is about 0.5 inches.

23. A method according to claim 11 and wherein the plasma is generated between an anode and a cathode and wherein a minimum distance between the prions and the closer of the anode and electrode is 1.5 inches.

24. A method according to claim 23 wherein the distance is one inch or less.

25. A method according to claim 24 wherein the distance between the prions and the anode is one inch or less.

26. A method according to claim 1 in which the hydrogen peroxide effects sterilization of the article.

27. A method according to claim 1 and further comprising increasing concentration of at least a portion of the hydrogen peroxide prior to contacting the prions therewith.

28. A method according to claim 27 wherein the step of increasing concentration of the hydrogen peroxide is performed by selectively removing water from the solution and exhausting that water through the sterilization chamber.

29. A method according to claim 1 and further comprising exciting gases surrounding the prions into the plasma phase and contacting the prions with the gases in the plasma phase.

30. A method according to claim 1 wherein the steps of steps of lowering pressure in the sterilization chamber and admitting the solution into the sterilization chamber comprise a cycle and wherein the cycle is repeated.

31. A method according to claim 30 wherein the cycle is repeated more than once.

32. A method according to claim 1 wherein during the step of contacting the article with hydrogen peroxide vapor, the vapor has a concentration of 10 mg/L or more.

33. A method according to claim 32 wherein during the step of contacting the article with hydrogen peroxide vapor, the vapor has a concentration of 15 mg/L or more.

34. A method according to claim 33 wherein during the step of contacting the article with hydrogen peroxide vapor, the vapor has a concentration of 20 mg/L or more.

35. A method according to claim 34 wherein during the step of contacting the article with hydrogen peroxide vapor, the vapor has a concentration of 25 mg/L or more.

36. A method according to claim 1 and further comprising the step of condensing a portion of the hydrogen peroxide vapor onto the article and wherein the concentration of that condensed hydrogen peroxide is at least 80% hydrogen peroxide by weight.

37. A method according to claim 36 wherein the concentration of that condensed hydrogen peroxide is at least 85% hydrogen peroxide by weight.

38. A method according to claim 37 wherein the concentration of that condensed hydrogen peroxide is at least 90% hydrogen peroxide by weight.

39. A method according to claim 38 wherein the concentration of the condensed hydrogen peroxide is at least 95% hydrogen peroxide by weight.

40. A method according to claim 36 and further comprising the step of evaporating at least a portion of that condensed hydrogen peroxide by pumping the sterilization chamber to a lower pressure.

41. A method of inactivating prions comprising the steps of: placing an article having a quantity of prions thereon into a sterilization chamber;contacting the article with a plasma to effect inactivation of the prions.

42. A method according to claim 41 wherein the plasma is formed from a gas comprising hydrogen peroxide.

43. A method according to claim 41 wherein the plasma density is at least 10 milliwatts/cm3.

44. A method according to claim 43 wherein the plasma density is at least 20 milliwatts/cm3.

45. A method according to claim 44 wherein the plasma density is at least 30 milliwatts/cm3.

46. A method according to claim 45 wherein the plasma density is at least 40 milliwatts/cm3.

47. A method according to claim 46 wherein the plasma density is at least 50 milliwatts/cm3.

48. A method according to claim 41 wherein the plasma is generated between an anode and a cathode and wherein a gap therebetween is less than 0.6 inches.

49. A method according to claim 48 wherein the gap is 0.5 inches or less.

50. A method according to claim 48 wherein the gap is about 0.5 inches.

51. A method according to claim 41 and wherein the plasma is generated between an anode and a cathode and wherein a minimum distance between the prions and the closer of the anode and cathode is 1.5 inches.

52. A method according to claim 51 wherein the distance is one inch or less.

53. A method according to claim 52 wherein the distance between the prions and the anode is one inch or less.