Ethylene oxide sterilization and aeration indicator

• US 4,671,936 A
• Filed: 12/30/1982
• Issued: 06/09/1987
• Est. Priority Date: 12/30/1982
• Status: Expired due to Term

• Current Assignee: American Sterilizer Company (Steris Corporation)
• Original Assignee: American Sterilizer Company (Steris Corporation)
• Inventors: Barron, William R.
• Primary Examiner(s): NOT, DEFINED
• Assistant Examiner(s): Johnson, William R.
• Application Number:
  US06/454,585
• Time in Patent Office: 1,622 Days
• Field of Search: 422/30, 422/34, 422/55, 422/56, 422/57, 422/86, 436/1, 436/38, 436/93, 436/163, 210/94
• US Class Current: 422/416
• 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: G01N 31/226 for investigating the degree of sterilisation

Abstract

Means are provided for the monitoring of a sterilization procedure employing alkylene oxide, particularly ethylene oxide, to sterilize medical equipment, especially heat-sensitive equipment, and especially for monitoring the aeration of the so-sterilized goods and articles to desorb the retained alkylene oxide, which means employ interaction of the alkylene oxide with a cation-exchange resin and subsequent aeration of the cation exchange resin coupled with pH indicator means sensitive to changes in the ion exchange resin effected by the alkylene oxide employed in the sterilization and subsequently by the air employed in the desorption step.

Claims

1. Means for monitoring and determining the effective end point of sterilization conditions in which an alkylene oxide is employed to sterilize in a sterilization chamber medical goods and articles including packs containing surgical instruments, and for monitoring and determining the effective end point of a process of aeration of so-sterilized goods and articles to desorb the same of the alkylene oxide, said means consisting essentiallv of a strong acid cation exhange resin in a discrete form suitable for inclusion with the goods during sterilization and aeration and a color changing pH indicator means associated with the said discrete form of cation exchange resins;

said cation resin and said pH indicator means undergoing a two step reaction to monitor and determine the effective end point of sterilization wherein said cation exchange resin reacts with the alkylene oxide to effect a change in the pH of said cation exchange resin and said of pH indicator means registers such change by displaying a distinct color response visible to the naked eye; and

said cation exchange resin and said pH indicator means being suitable for subsequently monitoring the effectiveness of the aeration process wherein said cation exchange resin undergoes an additional change which effects a reversion of the pH indicator means to its original precolored state.

2. The means of claim 1 in which the alkylene oxide is ethylene oxide and the cation exchange resin is in the discrete form of a gas permeable package of small, predetermined sized particles of a strong acid synthetic cation exchange resin which has been dyed with a selected pH indicator that changes color to reflect that reduction in hydrogen ion concentration on the surface of the said resin which is effected by the ethylene oxide adsorbed on and reacted with the said surface during ethylene oxide sterilization and that subsequently reverts to its original color to reflect the alteration of the surface of the said resin effected by air employed in desorbing the goods being sterilized of residual ethylene oxide.

3. Means for monitoring and determining the effective end point of sterilization conditions in which ethylene oxide is employed to sterilize in a sterilization chamber medical goods and articles including packs containing surgical instruments, and for monitoring and determining the effective end point of a process of aeration of so-sterilized goods and articles to desorb the same of the ethylene oxide, said means consisting essentially of a powdered strong acid cation exchange resin of small predetermined sized particles in a gas permeable, at least oartially transparent envelope suitable for inclusion with the goods during sterilization and aeration and a color changing pH indicator means deposited on the surface of the said cation exchange resin, said envelope permitting (1) penetration of ethylene oxide and of air when placed respectively in a sterilization zone and a subsequently an aeration zone and (2) visual inspection upon termination of said sterilization and said aeration;

said cation exchange resin and said pH indicator means undergoing a two step reaction to monitor and determine the effective end point of sterilization wherein said cation exchange resin reacts with the ethylene oxide to effect a reduction in hydrogen ion concentration on the surface of said cation exchange resin to change the pH of said cation exchange resin and said pH indicator means registers such change by displaying a distinct color response visible to the naked eye; and

said cation exchange resin and said pH indicator means being suitable for subsequently monitoring the effectiveness of the aeration process wherein said cation exchange resin undergoes an additional change which effects a reversion of the pH indicator means to its original precolored state.

10. The means of claim 3, 4, or 5 in which the pH indicator is Quinidine red.

11. The means of claim 3, 4, or 5 in which the pH indicator is 4 phenylazodiphenylamine.

12. The means of claim 3, 4, or 5 in which the pH indicator is Metanil yellow.

13. The means of claim 3, 4, or 5 in which the pH indicator is Erythrosin B.

4. Means for monitoring and determining the effective end point of sterilization conditions in which an alkylene oxide is employed to sterilize in a sterilization chamber medical goods and articles including packs containing surgical instruments, and for monitoring and determining the effective end point of a process of aeration of so-sterilized goods and articles to desorb the same of the alkylene oxide, said means consisting essentially of a powdered strong acid cation exchange resin suoported upon a substrate consisting of a plastic or cellulosic film suitable for inclusion with the goods during sterilization and aeration and a color changing pH indicator means associated with the said cation exchange resin;

said cation exchange resin and said pH indicator means undergoing a two step reaction to monitor and determine the effective end point of sterilization wherein said cation exchange resin reacts with the alkylene oxide to effect a change in the pH of said cation exchange resin and said nH indicator means registers such change by displaying a distinct color response visible to the naked eye; and

said cation exchange resin and said pH indicator means being suitable for subsequently monitoring the effectiveness of the aeration process wherein said cation exchange resin undergoes an additional change which effects a reversion of the pH indicator means to its original precolored state.

5. Means for monitoring and determining the effective end point of sterilization conditions in which an alkylene oxide is employed to sterilize in a sterilization chamber medical goods and articles including packs containing surgical instruments, and for monitoring and determining the effective end point of a process of aeration of so-sterilized goods and articles to desorb the same of the alkylene oxide, said means consisting essentially of a strong acid cation exchange resin in a comminuted from and incorporated in a thermoplastic resin composition so as to form a flexible transparent plastic disk suitable for inclusion with the goods during sterilization and aeration and a color changing pH indicator means associated with the said cation exchange resin;

said cation exchange resin and said pH indicator means undergoing a two step reaction to monitor and determine the effective end point of sterilization wherein said cation exchange resin reacts with the alkylene oxide to effect a change in the pH of said cation exchange resin and said pH indicator means registers such change by displaying a distinct color response visible to the naked eye; and

said cation exchange resin and said pH indicator means being suitable for subsequently monitoring the effectiveness of the aeration process wherein said cation exchange resin undergoes an additional change which effects a reversion of the pH indicator means to its original precolored state.

6. The means of claim 5 in which the flexible transparent plastic disk consists of a composition cured at high temperature comprising a modified chlorethylene polymer.

7. Means for monitoring and determining the effective end point of sterilization conditions in which an alkylene oxide is employed to sterilize in a sterilization chamber medical goods and articles including packs containing surgical instruments, and for monitoring and determining the effective end point of a process of aeration of so-sterilized goods and articles to desorb the same of the alkylene oxide, said means consisting essentially of a strong acid cation exchange resin in a pellet from of compressed comminuted exchange resin suitable for inclusion with the goods during sterilization and aeration and a color changing pH indicator means associated with the said pellet form of cation exchange resin;

said cation exchange resin and said pH indicator means undergoing a two step reaction to monitor and determine the effective end point of sterilization wherein said cation exchange resin reacts with the alkylene oxide to effect a change in the pH of said cation exchange resin and said pH indicator means registers such change by displaying a distinct color response visible to the naked eye; and

said cation exchange resin and said pH indicator means being suitable for subsequently monitoring the effectiveness of the aeration process wherein said cation exchange resin undergoes an additional change which effects a reversion of the pH indicator means to its original precolored state.

8. The means of claim 7 in which the cation exchange resin is in admixture with an absorbent.

9. The means of claim 8 in which the absorbent is silica gel.