Dual current method and apparatus for sterilization of medical devices

• US 6,146,586 A
• Filed: 05/28/1998
• Issued: 11/14/2000
• Est. Priority Date: 05/28/1998
• Status: Expired due to Term

• Current Assignee: Montana State University
• Original Assignee: The Research & Development Institute, Inc.
• Inventors: Costerton, J. William, McLeod, Bruce R.
• Primary Examiner(s): MCKANE, ELIZABETH L
• Application Number:
  US09/084,959
• Time in Patent Office: 901 Days
• Field of Search: 422/22, 422/23, 422/28, 422/292, 422/300, 204/554, 204/660, 204/272, 204/287, 204/297 R, 204/297 W
• US Class Current: 422/23
• CPC Class Codes: A61L 2/035 Electrolysis
• CPC Class Codes: A61L 2/18 Liquid substances or solutions comprising solids or dissolved gases
• CPC Class Codes: A61L 2/24 Apparatus using programmed or automatic operation

Abstract

In order to completely sterilize all of the surfaces of a medical instrument on which biofilms are apt to form, the device is immersed in a container containing an antibiotic solution in a manner wherein all of the contaminated surfaces are forced into intimate contact with the antibiotic solution. A first current is applied to a first electrode disposed at one end of the container to establish a first current flow about the exterior of the instrument between the first electrode and a second distal electrode which is either proximate or in direct contact with an end portion of the device. A second current is passed between a third electrode which is either in electrical contact with a part of the instrument that is not immersed in the antibiotic solution, or immersed in the solution has been forced into the interior of the device, and the second electrode via a second current path which extends through the interior of the instrument. The two currents are applied for a predetermined time selected to achieve the sterilization of any biofilms which have formed.

Claims

1. A method of sterilizing an instrument comprising the steps of:

immersing the instrument in an antibiotic solution;

disposing a portion of the instrument in proximity to a first and second electrode;

connecting a second electrode to a portion of the device and establishing a first current path between the first and second electrodes;

immersing a third electrode in the antibiotic solution so as to be distal from the first electrode;

interconnecting the third electrode and the second electrode to establish a second current path;

passing a first current through the first current path;

passing a second current through the second current path; and

maintaining the passage of the first and second currents through the first and second current paths for a predetermined time.

2. A method of sterilizing as set forth in claim 1, wherein said step of immersing comprises the step of pressurizing the antibiotic solution so that intimate contact between the surfaces of the instrument which require sterilization and the antibiotic solution occurs.

3. A method of sterilizing as set forth in claim 1, further comprising the step of arranging the third electrode to surround a portion of the instrument which is immersed in the antibiotic solution and which is distal from the first electrode.

4. A method of sterilization as set forth in claim 1, further comprising the step of controlling the first current to have an amperage of 2-10 ma.

5. A method of sterilization as set forth in claim 4, further comprising the step of controlling the first current to have a voltage of 0.5-20 volts.

6. An apparatus for sterilizing an instrument comprising:

a container having an opening, said container containing a liquid containing an antibiotic;

seal means disposed at the opening of said container, said seal being arranged to permit the insertion of an instrument into the container and to establish a fluid-tight seal about the periphery of the instrument and prevent fluid communication between the interior of the container and an ambient atmosphere;

a first electrode disposed in a first portion of the container;

a second electrode disposed in a second portion of the container, said second electrode being distal from said first electrode and adapted to be proximate an end of the instrument upon its insertion into said container;

a first electrical circuit electrically interconnecting the first and second electrodes, said first electrical circuit including a power source for selectively applying current across the first and second electrodes and through a first current path interconnecting the first and second electrodes; and

a second electrical circuit, said second electrical circuit including a third electrode which is in contact with a portion of the instrument, said second electrical circuit being electrically connected with said second electrode and including a power source for selectively supplying a current through a second current path which extends from said third electrode, through the instrument, to said second electrode.

7. An apparatus as set forth in claim 6, wherein said instrument comprises a medical instrument and which includes an internal passage structure into which the liquid containing the antibiotic is forced as the instrument is inserted into said container, and wherein the second current path extends through the interior of the instrument.

8. An apparatus for sterilizing an instrument comprising:

means for immersing a portion of the instrument in a liquid containing an antibiotic in a manner wherein at least a portion of the liquid is pressurized and forced into cavities within the instrument;

means for passing a first current along a first current path which extends through the liquid solution surrounding the exterior of the instrument to an electrode which is proximate a portion of the instrument which is immersed in the liquid; and

means for passing a second current through an interior passage structure of the instrument to the electrode along a second current path which extends through the interior of the instrument.

9. A method for sterilizing an instrument comprising the steps of:

immersing a portion of the instrument in a liquid containing an antibiotic in a manner wherein at least a portion of the liquid is pressurized and forced into cavities included within the instrument;

passing a first current through the liquid surrounding the instrument to an electrode which is proximate a portion of the instrument which is immersed in the liquid to effect sterilization of an exterior surface of the instrument; and

passing a second current through an interior of the instrument to the electrode in contact the instrument to effect sterilization of an interior surface of the instrument.

10. A method of sterilizing a medical instrument that has a biofilm on an exterior surface and a biofilm on an interior surface comprising:

immersing the exterior surface and the interior surface having the biofilms thereon in a liquid electrolyte;

establishing a first electric current path along the exterior surface, and establishing a second electric current path along the interior surface; and

passing a first electric current through the first current path, and passing a second electric current through the second current path.

11. The method of claim 10, including positioning the medical instrument in a container of the liquid electrolyte and applying sufficient pressure on the liquid electrolyte to force liquid electrolyte into contact with the interior surface that is to be sterilized.

12. The method of claim 10, including positioning a first pair of electrodes in the liquid electrolyte adjacent the exterior surface to establish said first electric current path and applying a first voltage across the first pair of electrodes to induce said first electric current to flow along the first electric current path, and including positioning a second pair of electrodes in the liquid electrolyte to establish said second electric current path and applying a second voltage across second pair of electrodes to induce said second electric current to flow along said second electric current path.

13. The method of claim 12, including arranging one of the electrodes of said first pair of electrodes to also be one of the electrodes of said second pair of electrodes.

14. Apparatus for sterilizing a medical instrument that has an elongated inner tube with a first end and a second end mounted in an elongated housing that has an external peripheral surface, wherein said elongated inner tube has an interior surface surrounding a passage with a first opening at said first end and a second opening at or adjacent the second end, comprising:

a container with a top end and a bottom end, said container having an aperture in said top end that is large enough to allow insertion of said medical instrument through said opening into said container;

liquid electrolyte in said container;

a first electrode disposed in said electrolyte adjacent said top end;

second electrode disposed in said liquid electrolyte adjacent said bottom end;

a voltage source connected to said first electrode and to said second electrode; and

a second voltage source connected electrically to a third electrode in said passage and to a stud electrode disposed in said liquid electrolyte adjacent said bottom end of said container.

15. The apparatus of claim 14, wherein said third electrode is said inner tube.

16. The apparatus of claim 14, wherein said second electrode is said stud electrode.

17. The apparatus of claim 14, including a seal around said aperture in said top end that is sized and shaped to fit snugly enough around the external peripheral surface of the housing to prevent passage of fluid between said seal and said external peripheral surface at a pressure sufficient to force said liquid electrolyte in said passage to said second opening.

18. Apparatus for sterilizing a medical instrument that has an elongated inner tube with a first end and a second end mounted in an elongated housing wherein said elongated inner tube has an interior surface surrounding a passage with a first opening at said first end and a second opening at or adjacent the second end, comprising:

a container with a top end and a bottom end, said container having an aperture in said top end that is large enough to allow insertion of said medical instrument through said opening into said container;

liquid electrolyte in said container;

an external electrode positioned in said liquid electrolyte adjacent said bottom end;

a voltage source connected electrically to said external electrode, and a means for connecting said voltage source to an internal electrode in the passage.

19. The apparatus of claim 18, wherein said internal electrode is said inner tube.