Sterilization of elongate lumens

• US 6,162,395 A
• Filed: 08/17/1998
• Issued: 12/19/2000
• Est. Priority Date: 08/17/1998
• Status: Expired due to Fees

• Current Assignee: Enviromedical Systems Incorporated
• Original Assignee: Enviromedical Systems Incorporated
• Inventors: Kowanko, Nicholas
• Primary Examiner(s): JASTRZAB, KRISANNE MARIE
• Application Number:
  US09/135,146
• Time in Patent Office: 855 Days
• Field of Search: 422/33, 422/28, 422/40, 422/292, 422/294, 422/295, 422/297, 422/300
• US Class Current: 422/33
• CPC Class Codes: A61B 1/125 using fluid circuits
• CPC Class Codes: A61L 2/204 Formaldehyde
• CPC Class Codes: A61L 2/206 Ethylene oxide
• CPC Class Codes: A61L 2/208 Hydrogen peroxide
• CPC Class Codes: A61L 2202/122 Chambers for sterilisation
• CPC Class Codes: A61L 2202/24 Medical instruments, e.g. endoscopes, catheters, sharps

Abstract

A method of and system for sterilizing the internal surfaces of one or more elongate relatively narrow passages of interest contained in a device of interest, said passages having end openings and being susceptible of sustaining flow therealong by inducing a positive flow of sterilizing gas through each passage of interest in a selected direction. Gas flow through a device of interest is caused by a passive two-chamber device which generates a transient pressure gradient between the ends of the lumens of the device in response to externally imposed variations of pressure. Sterilant gas is provided from outside the two chamber systems.

Claims

1. A method of gas phase sterilization of devices of interest of a class having internal surfaces which include one or more elongate passages of interest, said passages having end openings and being susceptible of sustaining a flow of gas therealong the method comprising the steps of:

(a) connecting an empty removable closed chamber to said devices of interest to one end of said passages of interest, said closed chamber being open to each said passage of interest and wherein said closed chamber has a volume greater than the total volume of all connected passages of interest to be sterilized;

(b) establishing a net flow of sterilant gas through each passage of interest in a selected direction by subjecting the one or more end openings not connected to said removable closed chambers to transient alternating cycles of decreasing pressure and pressurization thereby producing a directionally reversing net flow through said one or more passages of interest;

(c) introducing sterilant vapor with said repressurization steps of said cycles; and

(d) varying said pressure sufficiently that said net flow in each direction exceeds the volume of said one or more passages;

(e) providing vapor permeability for sterilizing the portion of said devices of interest at the connection with said closed chamber.

2. The method of claim 1, further comprising the step of:

(f) enclosing said device of interest with said removable closed chamber attached in a storage container having a gas permeable, external access port for evacuation and pressurization.

3. The method of claim 2 further comprising the step of:

(g) enclosing said storage container in a larger sterilization vessel for pressure cycling.

4. The method of claim 1 wherein said device of interest contains a single passage of interest.

5. The method of claim 1 wherein said device of interest contains a plurality of passages of interest.

6. A gas sterilization system to sterilize devices of a class having an elongate, narrow-internal passage of interest, said system comprising:

(a) a first sterilization chamber having an internal volume and an opening for receiving an end portion of a storage package containing a device to be sterilized, said end portion further containing one end of said passage of interest and a vapor permeable gas transport area;

(b) a storage package for containing the device of interest in a generally straight configuration and containing a plurality of vapor permeable gas transport areas;

(c) a second sterilization chamber for containing said first chamber and said package, one end of said package being received in said first sterilization chamber;

(d) said second sterilization chamber having a connection device to connect to an evacuation system disposed to draw a vacuum in said second chamber to thereby reduce the pressure in said package and said first sterilization chamber at an unequal rate and a pressurized sterilant gas introducing system disposed to introduce sterilant gas into both of said chambers at an unequal rate.

7. The gas sterilization system of claim 6 wherein said first sterilization chamber further comprises a vapor permeable area open to said second sterilization chamber.

8. The gas sterilization system of claim 6 wherein said first chamber clamps on to said storage package.

9. The gas sterilization system of claim 7 wherein said first chamber clamps on to said storage package.

10. A method of gas phase sterilization for devices of interest of a class having internal surfaces which include one or more elongate passages of interest, said passages of interest having end openings and being susceptible of sustaining a flow of gas therealong, the method comprising the steps of:

(a) providing an ambient atmosphere containing sterilant vapor;

(b) exposing both said end openings of each passage simultaneously to an increasing or decreasing pressure wherein each end of a given passage is exposed to a different transitory pressure function to thereby establish a net flow of sterilant gas through each passage of interest in a selected direction; and

(c) alternately and simultaneously cyclically exposing said end openings to decreasing and increasing pressure change thereby alternately reversing the direction of net flow of sterilant gas through each passage of interest, wherein the volume of said net flow induced through each passage of interest in each direction during each cycle is greater than the volume of that passage of interest.

11. The method of claim 10 wherein the device of interest contains a plurality of passages of interest.

12. A method of gas phase sterilization for devices of interest of a class having characteristic internal surfaces which include one or more elongate passages of interest, said passages of interest having end openings and being susceptible of sustaining a flow of gas therealong, the method comprising the steps of:

(a) enclosing said device of interest in a package having two chambers, a common partition member forming said chambers in said package, said device breaching said partition member such that each end opening of each said passage of interest lies in a different one of said two chambers and wherein at least one of said two chambers has an externally communicating gas transport capability area;

(b) placing said package in a larger sterilization chamber;

(c) providing an ambient atmosphere containing sterilant vapor;

(d) exposing said package to an increasing or decreasing ambient pressure, the package being constructed so that each end of a given passage is thereby exposed to a different transitory pressure function to thereby establish a net flow of sterilant gas through each passage of interest in a selected direction;

(e) subjecting said package to cycling pressurization and vacuum steps using pressure modulated sterilant gas thereby alternately reversing the direction of net flow of sterilant gas through each passage of interest; and

(f) wherein the relative volumes of the two chambers of the package in combination with the relative externally communicating vapor transport capabilities of the two chambers are designed in combination to produce a desired net flow volume of sterilant gas greater than the volume of the passages of interest to be sterilized at a given pressurization and vacuum cycle modulation.

13. The method of claim 12 wherein both of the compartments have an externally communicating gas permeable area.

14. The method of claim 12 wherein one of said compartments is larger than the other.

15. The method of claim 12 wherein said device of interest breaches said common partition between said two chambers through an opening that is surrounded by a vapor transporting gas permeable medium such that areas of the device in the vicinity of the partition are sterilized.

16. The method of claim 12 wherein said device of interest passes between said two chambers through an opening in said common partition in a manner and such that sterilant material may pass between said partition and said device.

17. The method of claim 12 wherein only one of the chambers has an externally communicating gas permeable area.

18. The method of claim 12 wherein the effective rate of evacuating or pressurizing each of said separate chambers is accomplished at least in part by providing externally connecting gas permeable areas in said chambers having different vapor transport capacities.

19. The method of claim 12 wherein the relative volumes of the chambers and the relative vapor transport capabilities of the gas permeable areas in combination are sufficient to produce a net flow volume of sterilant gas greater than the volume of the passages of interest to be sterilized.

20. The method of claim 12 wherein said chambers are of unequal volume and the size and size ratio of the volumes of said sterilization chambers are sufficient to produce a net flow volume of sterilant gas greater than the volume of the passages of interest to be sterilized.

21. A sterilization container for containing a device of interest to be sterilized of a class having internal surfaces which include an elongate passage of interest comprising:

(a) a shaped cassette module intended for a particular device of interest including a hollow body and a lid and enclosing a volume;

(b) a partition in said sterilization cassette to divide said volume into two compartments, said partition further being provided with one or more partition openings therein to accommodate the nesting of a portion of a device of interest to be sterilized extending therethrough such that each internal passage of interest to be sterilized in said device can be disposed to have a passage opening exposed in each of said compartments;

(c) said cassette being provided with a gas permeable vapor transport area open to the exterior in at least one of the two compartments; and

(d) wherein said cassette is adapted to be contained in a larger sterilizing vessel during the sterilization operation.

22. The container of claim 21 wherein the combination of relative sizes of said two compartments and vapor transport capacities of said one or more gas permeable accesses to external ambient are such that exposure of the entire cassette to an environment of desired reduced pressure will result in a desired amount of net transient flow induced along the length of each internal passage of interest of a device mounted in said cassette in one direction and external pressurization above the pressure in said cassette will induce a desired amount of net transient flow in each of said internal passages of interest in the opposite direction wherein the amount of net transient flow in each of said internal passages of interest in each direction is greater than the volume of each passage of interest.

23. The container of claim 21 further comprising gas permeable material at said partition openings to expose the portion of each device of interest extending therethrough within each of said openings to the ambient atmosphere.

24. The container of claim 21 wherein said partition openings are designed for clearance with respect to each device of interest passing therethrough.

25. The container of claim 21 wherein the cassette is provided with a gas permeable vapor transport area open to the exterior in both of said compartments.

26. The container of claim 25 wherein said vapor transport areas in said two compartments have unequal vapor transport capacities for allowing the passage of vapor between said cassette and external ambient.

27. The container of claim 25 wherein said compartments are of unequal volume and gas permeable access areas in said two compartments are substantially equal in transport ability.

28. The container of claim 21 wherein said two compartments of said cassette are unequal in volume.

29. The container of claim 28 wherein the cassette is provided with a gas permeable access area open to the exterior in both of said compartments.

30. The container of claim 27 wherein said two compartments of said cassette are unequal in volume.

31. The container of claim 21 wherein the two compartments are of unequal size and gas permeable access areas open to external ambient are located in both compartments.

32. The container of claim 31 wherein the volumes of said two compartments are sufficiently large and different such that net transient flow induced through each passage of interest during a normal pressure cyclic pressure change is greater than the volume of each passage of interest.

33. A gas sterilization system for the sterilization of devices having one or more discreet, elongate, internal passages of interest comprising:

(a) a sterilization container comprising;

(1) a first sterilization chamber enclosing a first volume;

(2) a second sterilization chamber enclosing a second volume in said first sterilization chamber, said second sterilization chamber being smaller than said first chamber wherein said second sterilization chamber is a removable closed chamber connected to one end of said passages of interest wherein said removable closed chamber has a volume greater than the total volume of said passages;

(3) partition barrier to separate said first and second sterilization chambers, said barrier means further being provided with one or more device passage openings therein to accommodate passage of a portion of a device to be sterilized therethrough such that each internal passage of interest to be sterilized in said device has a passage opening exposed to each of said chambers;

(4) means selected from the group consisting of a layer of gas permeable material and a gas permeable opening in each of said one or more device passage openings to permit sterilant vapor to reach and sterilize that portion of a device situated in a barrier opening;

(b) evacuation system disposed to draw a vacuum in both of said chambers reducing the pressure in said chambers at an unequal rate;

(c) pressurized sterilant gas introducing system disposed to introduce sterilant gas into both of said chambers to repressurize said chambers at an unequal rate; and

(d) control system for sequentially operating said evacuation system and said sterilant gas introducing system in a manner to induce a reversing transient net flow between the chambers in each internal passage of interest.

34. The gas sterilization system of claim 33 wherein said second sterilization chamber is a removable closed chamber connected to one end of said passages of interest wherein said removable closed chamber has a volume greater than the total volume of said passages.

35. The gas sterilization system of claim 33, further comprising a sterilization vessel for containing one or more of said sterilization containers, said sterilization vessel being connected to said evacuation system and said sterilant gas phase introducing system.