Methods and apparatus for sterilizing contaminated devices

• US 20040001783A1
• Filed: 06/26/2002
• Published: 01/01/2004
• Est. Priority Date: 06/26/2002
• Status: Active Grant

• Current Assignee: John G. Bowen
• Original Assignee: John G. Bowen
• Inventors: Bowen, John G.
• Granted Patent: US 7,018,592 B2
• Time in Patent Office: Days
• US Class Current: 422/292
• CPC Class Codes: A61L 2/07 Steam
• CPC Class Codes: A61L 2/24 Apparatus using programmed or automatic operation
• CPC Class Codes: A61L 2/28 Devices for testing the effectiveness or completeness of sterilisation, e.g. indicators which change colour apparatus involving enzymes or microorganisms C12M1/34; methods involving enzymes or microorganisms C12Q1/00
• CPC Class Codes: A61L 2202/122 Chambers for sterilisation
• CPC Class Codes: A61L 2202/14 Means for controlling sterilisation processes, data processing, presentation and storage means, e.g. sensors, controllers, programs
• CPC Class Codes: A61L 2202/24 Medical instruments, e.g. endoscopes, catheters, sharps

Abstract

A self-contained, single manual step unit for thermally sterilizing dental and medical instruments is disclosed. The unit, which requires only activation of a single manual switch and which controls an autoclaving cycle by monitoring temperature of matter which changes states between solid and liquid at a predetermined temperature, provides an effective autoclaving instrument. In disclosed embodiments, each unit comprises a protective housing with a pressure containing releasible lid, a heated vessel and a cooling assembly. Thermal regulation and autoclaving timing is determined by mass and thermal characteristics of the matter and by an electrical control circuit comprised primarily of electric heaters and thermally controlled switches. Steam for autoclaving is provided by capsules or other water containers disposed within a well of the vessel at the beginning of an autoclaving cycle. Also disclosed are parts containers or transporters or which may be displaced into the well along with contents to be sterilized. Such parts containers or transporters may be sharps containers, bags and medical device wraps. The bags may be bicompartmental in form wherein one of the compartments contains water and is perforateable to deliver autoclaving steam for sterilizing items disposed in the other compartment. Parts of sharps containers may be sealed together as a result of melting of synthetic resinous material resident on the sharps container during a sterilization cycle.

Claims

1. A self-contained, single manual step unit for thermally sterilizing dental and medical instruments and other contaminated items comprising:

an insulating and protective housing comprising an orifice for ingress and egress of items to be sterilized;

a vessel disposed within said housing which comprises an inner contiguous vertical wall, which is closed at the bottom to form a medially disposed well wherein items are sterilized and cooled thereafter, and unobstructed at the top which provides an accessible opening through said orifice;

said unit further comprising a thermal regulation assembly disposed in caloric communication with said vessel, said assembly comprising an inner wall and a juxtaposed outer wall separated therefrom and sealed thereto to form a chamber;

a predetermined quantity of matter, which changes state at a predetermined temperature which is consistent with sterilizing, hermetically sealed within said chamber;

a disengageable lid which covers, protects and seals said accessible opening when engaged and which permits access to said well when disengaged;

at least one heater disposed in caloric communication with said matter, said heater having adequate thermal output to heat the matter in excess of the change-of-state temperature of the matter;

a source of water disposed within the well, at least a portion of which is transformed to steam as part of the sterilization cycle; and

an electrical control system which limits duration of the sterilization cycle and automatically initiates a cooling cycle at the end of the sterilization cycle.

2. A self-contained, single manual step unit for thermally sterilizing dental and medical instruments and other contaminated items according to claim 1 wherein said inner contiguous vertical wall and said thermal regulation assembly inner wall are the same wall.

3. A self-contained, single manual step unit for thermally sterilizing dental and medical instruments and other contaminated items according to claim 1 further comprising a container in which items to be sterilized are loaded and displaced into the vessel well.

4. A self-contained, single manual step unit for thermally sterilizing dental and medical instruments and other contaminated items according to claim 3 wherein said container is plastic.

5. A self-contained, single manual step unit for thermally sterilizing dental and medical instruments and other contaminated items according to claim 4 wherein said plastic container is a sharps container.

6. A self-contained single manual step unit for thermally sterilizing dental and medical instruments and other contaminated items according to claim 5 wherein said plastic container comprises deposits of synthetic resinous material disposed to melt during sterilization and thereby be displaced to provide a seal.

7. A self-contained single manual step unit for thermally sterilizing dental and medical instruments and other contaminated items according to claim 6 wherein said seal is a locking seal.

8. A self-contained single manual step unit for thermally sterilizing dental and medical instruments and other contaminated items according to claim 6 wherein said seal is a hermetic seal.

9. A self-contained single manual step unit for thermally sterilizing dental and medical instruments and other contaminated items according to claim 6 wherein said synthetic resinous material is urethane.

10. A self-contained, single manual step unit for thermally sterilizing dental and medical instruments and other contaminated items according to claim 1 wherein said thermal regulation assembly comprises a cooling subassembly.

11. A self-contained, single manual step unit for thermally sterilizing dental and medical instruments and other contaminated items according to claim 10 wherein said cooling subassembly comprises a cooling coil disposed in caloric communication with said thermal regulation assembly inner wall.

12. A self-contained, single manual step unit for thermally sterilizing dental and medical instruments and other contaminated items according to claim 1 wherein said electrical control system comprises at least one unit status indicator light.

13. A self-contained, single manual step unit for thermally sterilizing dental and medical instruments and other contaminated items according to claim 12 wherein said at least one status indicator light comprises a red “

heater on”

indicating light.

14. A self-contained, single manual step unit for thermally sterilizing dental and medical instruments and other contaminated items according to claim 12 wherein said at least one status indicator light comprises a blue “

cooling cycle in progress”

indicating light.

15. A self-contained, single manual step unit for thermally sterilizing dental and medical instruments and other contaminated items according to claim 12 wherein said at least one status indicator light comprises a green “

sterilization cycle complete”

indicating light.

16. A self-contained, single manual step unit for thermally sterilizing dental and medical instruments and other contaminated items according to claim 1 wherein said electrical control system comprises an audio signal to provide a low pressure potential vessel leaking) warning.

17. A self-contained, single manual step unit for thermally sterilizing dental and medical instruments and other contaminated items according to claim 1 wherein said matter is paraffin.

18. A self-contained, single manual step unit for thermally sterilizing dental and medical instruments and other contaminated items according to claim 1 wherein said source comprises a perforateable capsule.

19. A self-contained, single manual step unit for thermally sterilizing dental and medical instruments and other contaminated items according to claim 18 further comprising a medical wrap which protectively encloses said capsule and items to be sterilized and which is disposed in said well throughout the sterilization cycle.

20. A self-contained, single manual step unit for thermally sterilizing dental and medical instruments and other contaminated items according to claim 1 wherein said source is a packet formed in a plastic bag.

21. A self-contained, single manual step unit for thermally sterilizing dental and medical instruments and other contaminated items according to claim 20 wherein said capsule contains ultra pure water (i.e. having a specific conductance of less than or equal to 0.055 micromhos/centimeter).

22. A self-contained, single manual step unit for thermally sterilizing dental and medical instruments and other contaminated items according to claim 1 wherein said capsule comprises a mark made of matter which noticeably changes color when a adequate sterilization cycle has been completed.

23. A self-contained, single manual step unit for thermally sterilizing dental and medical instruments and other contaminated items according to claim 22 wherein said mark is disposed upon a removable label whereby an indicator of completion of a sterilization cycle is readily transferred from the capsule to a reference log.

24. A self-contained, single manual step unit for thermally sterilizing dental and medical instruments and other contaminated items according to claim 1 wherein said electrical control system comprises a first temperature sensitive switch which is in caloric communication with said matter and which resets to an open state to end the heating portion of the sterilization cycle when said matter reaches a predetermined temperate.

25. A self-contained, single manual step unit for thermally sterilizing dental and medical instruments and other contaminated items according to claim 24 wherein said first temperature sensitive switch is a bimetal switch which is calibrated to automatically reset at 150°

centigrade.

26. A self-contained, single manual step unit for thermally sterilizing dental and medical instruments and other contaminated items according to claim 1 wherein said electrical control system comprises a second temperature sensitive switch which is in caloric communication with said mater and which closes to end the sterilization cycle and begin a cooling cycle when said matter reaches a predetermined temperature.

27. A self-contained, single manual step unit for thermally sterilizing dental and medical instruments and other contaminated items according to claim 26 wherein said second temperatures sensitive switch is a bimetal switch which closes at 120°

centigrade.

28. A method for thermally sterilizing dental and medical instruments and other contaminated items comprising the following steps:

providing;

an insulating and protective housing comprising an orifice for ingress and egress of items to be sterilized;

a vessel disposed within said housing which comprises;

an inner contiguous vertical wall which is closed at the bottom, to form a medially disposed well wherein items are sterilized and cooled thereafter and which is unobstructed at the top to provide an accessible opening though said orifice;

a thermal regulation assembly disposed in caloric communication with said well, said assembly comprising an inner wall and a juxtaposed outer wall separated therefrom and sealed thereto to form a chamber;

a disengageable lid which covers and seals said accessible opening when engaged and which permits access to said well when disengaged;

a quantity of matter, which changes state at a predetermined temperature which is consistent with sterilizing, hermetically sealed within said chamber;

at least one heater disposed in caloric communication with said matter, said heater having adequate thermal output to heat the matter in excess of a change-of-state temperature of the matter;

a source of liquid disposed within said well to provide a vaporizing liquid therein; and

an electrical control system comprising a sterilization cycle initiation switch, a first temperature sensor which is triggered by a first predetermined temperature of said matter, thereby determining an end of duration of the sterilization cycle and automatically initiating a cooling cycle, and an indicator which signals a sensed second predetermined temperature of said matter at the end of the cooling cycle;

displacing said lid for access into said well;

disposing the liquid source within said well;

disposing a preselected group of items of contaminated items into said well;

engaging said lid to provide a pressure seal over said orifice;

initiating a sterilization cycle by depressing the cycle initiating switch; and

upon appropriately noting indication of end of sterilization cycle by the completion indicator, disengaging and displacing the lid for access to sterilized items.

29. A method according to claim 28 wherein said first temperature sensor is a bimetal switch which is manually closed to initiate the sterilization cycle.

30. A method according to claim 29 comprising a step of automatically opening the bimetal switch at a first predetermined temperature which is above the state-change-temperature of the matter to end the heating portion of the sterilization cycle.

31. A method according to claim 30 wherein said automatically opening step occurs at a temperature of 150°

Centigrade.

32. A method according to claim 31 wherein said electrical control system comprises a second temperature sensor which is set to a first state at a second predetermined temperature which is less than the first predetermined temperature and which is set to a second state at a third predetermined temperature which is less than the second predetermined temperature.

33. A method according to claim 32 comprising an additional step of initiating a cooling cycle when said second sensor is set to the second state.

34. A method according to claim 28 wherein said source of liquid is a capsule having water sealed therein.

35. A method according to claim 34 comprising a step of perforating the capsule as a result of heating of the well thereby dispensing water, a portion of which changes to steam, within the well.

36. A unit for thermally sterilizing dental and medical instruments and other contaminated items comprising:

an insulating and protective housing comprising an orifice for ingress and egress of items to be sterilized;

a vessel disposed within said housing which comprises an inner contiguous vertical wall, which is closed at the bottom to form a medially disposed well wherein items are sterilized and cooled thereafter, and unobstructed at the top which provides an accessible opening through said orifice;

said unit further comprising a thermal regulation assembly disposed in caloric communication with sail vessel, said assembly comprising an inner wall and a juxtaposed outer wall separated therefrom and sealed thereto to form a chamber;

a disengageable lid which covers, protects and seals said accessible opening when engaged and which permits access to said well when disengaged;

at least one heater disposed in caloric communication with said matter, said heater having adequate thermal output to heat water to generate steam.

a container, placed within the well, containing the items to be sterilized;

a capsule of water disposed within the container, at least a portion of which is transformed to steam as part of the sterilization cycle, said being perforated when water is heated during the sterilization cycle; and

an electrical control system which limits duration of the sterilization cycle and temperature in the well to assure the container is not irreversibly damaged during the sterilization cycle.

37. A unit for thermally sterilizing dental and medical instruments and other contaminated items according to claim 36 further comprising a predetermined quantity of matter, which changes state at a predetermined temperature which is consistent with sterilizing, hermetically sealed within said chamber;

38. A unit for thermally sterilizing dental and medical instruments and other contaminated items according to claim 36 wherein said electrical control system aid automatically initiates a cooling cycle at the end of the sterilization cycle.

39. A unit for thermally sterilizing dental and medical instruments and other contaminated items according to claim 36 wherein said capsule comprises a frustoconically shaped package having a lid which in combination encloses and keeps pure a quantity of water, a portion of which is released during the sterilization cycle to provide the steam.

40. A unit for thermally sterilizing dental and medical instruments and other contaminated items according to claim 36 wherein said container is a protective wrap disposed about the capsule and items to be sterilized.

41. A unit for thermally sterilizing dental and medical instruments and other contaminated items according to claim 36 wherein said container is a synthetic resinous material which withstands and maintains containment of the items contained therein throughout the sterilization cycle.

42. A container for use in a thermally controlled and self contained sterilization unit for dental and medical instruments and other contaminated items comprising:

a first compartment and a second compartment;

said first compartment comprising an accessible orifice for ingress and egress of items to be sterilized therein while disposed in said unit;

said second compartment being sealed to contain a bolus of water therein;

said first and second compartments being separated by a seal which is breached by expansion of the water being heated and therefor producing steam in said second compartment, thereby communicating water and steam into said first compartment from said second compartment.

43. A sharps container comprising at least two parts joined to provide a container having an opening wherethrough sharps are displaced for storage in said container, at least one of the parts further comprising a pattern of material which is turned to a fluid state at an autoclaving temperature and flows into joints between the parts to form a seal between the parts.

44. A sharps container according to claim 43 wherein said seal is a locking seal.

45. A sharps container according to claim 43 wherein said seal is a hermetic seal.

46. A sharps container according to claim 43 wherein said material is urethane.