GB2105591A

GB2105591A - Combined gaseous hydrogen peroxide sterilizing chamber and storage unit for sterilized goods

Info

Publication number: GB2105591A
Application number: GB08225333A
Authority: GB
Inventors: Jack H Young; Thomas Brendgord
Original assignee: American Sterilizer Co
Current assignee: American Sterilizer Co
Priority date: 1981-09-08
Filing date: 1982-09-06
Publication date: 1983-03-30
Also published as: DE3233166A1; JPS5892356A; GB2105591B

Abstract

A method and apparatus for both sterilizing and storing goods e.g. medical instruments in the same container. A portable, sealable cassette (10) suitable for use with hydrogen peroxide gas as the sterilant is releasably connected via quick disconnect valves 16 to the corresponding valves 18 of master sterilization unit 20 to a source (32) of hydrogen peroxide gas to effect sterilization of articles within the cassette. Thereafter the cassette (10) is disengaged from the source (32) of hydrogen peroxide gas and may be stored in sealed containers until the sterilized articles are used. <IMAGE>

Description

SPECIFICATION Combined gaseous hydrogen peroxide sterilizing chamber and storage unit for sterilized goods Field of the Invention This invention relates to a method and apparatus for both sterilizing and storing goods in the same container; more particularly for providing a portable enclosure for use as a gaseous hydrogen peroxide sterilizing chamber and thereafter as a storage means for sterilized goods.

Description of the Prior Art The use of hydrogen peroxide gas as a sterilant is well known; see U.S. Patents Nos. 4,169,123 and 4,169,124. The practical application of gaseous hydrogen peroxide sterilization, however, is complicated by the fact that the vapor, at concentration levels contemplated by the aforesaid patents, does not readily penetrate commonly used wrapping materials for sterilizable goods. This characteristic diminishes the advantages offered by gaseous hydrogen peroxide sterilization for sterilizing goods that traditionally are stored in the wrapping materials for future use.

Such goods would include, for example, surgical instruments which must be maintained in a sterile condition until the sterile package is opened in the operating theatre. The practical application of gaseous hydrogen peroxide in sterilization processes also is complicated by the characteristics of hydrogen peroxide; namely, its tendency to degrade and to be absorbed in other materials.

Flexible packages long have been used to contain individual articles during sterilization and thereafter during storage; see e.g. Andersen et al.

U.S. Patent No. 3,630,665. Such flexible packages have only limited application, however, because they require complex apparatus for the introduction of sterilant into the packages and they obviously are not useful in sterilization cycles that involve the maintenance of pressure differentials across the walls of the container; e.g.

vacuum and pressure cycles.

Individual rigid wall containers for carrying articles to be sterilized within the containers are known. Ray U.S. Patent No. 3,561,918 discloses a medical case for carrying an instrument to be sterilized and thereafter transported in a sterile condition. The Ray patent contains no disclosure or suggestion, however, of using hydrogen peroxide gas as a sterilant and thus no appreciation for the peculiar characteristics of that material as alluded to above.

Summary of the Invention The present invention overcomes the sterilant penetrability problem associated with gaseous hydrogen peroxide sterilization by providing a combined sterilization chamber and storage unit for sterile articles. By employing the present invention, the need for wrapping materials is eliminated, and thus gaseous hydrogen peroxide directly contacts the articles to be sterilized. The invention also takes into account the degradation and absorbency problems associated with hydrogen peroxide.

More particularly, the present invention provides a method for sterilizing goods in unwrapped condition with hydrogen peroxide gas and thereafter storing the goods in sterile condition without removing them from their sterilizing chamber, comprising the steps of: providing a portable, sealable enclosure for the goods to be sterilized, the enclosure being substantially nonabsorbent to hydrogen peroxide and being capable of withstanding a pressure differential across its walls; loading the goods into the enclosure and sealing it; providing a source of hydrogen peroxide gas; releasably connecting the enclosure to the source of hydrogen peroxide gas to establish fluid communication between the source and the interior of the enclosure; contacting the goods within the enclosure with hydrogen peroxide gas to effect sterilization of the goods; withdrawing said hydrogen peroxide gas from said enclosure; disengaging the enclosure from the source of hydrogen peroxide gas; and storing the enclosure in a sealed condition until the sterile goods therein are used.

The present invention also provides apparatus for sterilizing articles and maintaining the sterility of the articles during transport and storage, comprising, in combination: a plurality of portable sterilization chambers, each chamber being hermetically sealable and having interiorly disposed means for supporting the articles in spaced-apart relationship; a main housing adapted to receive at least one of said chambers in a fixed orientation for processing; means within the housing for sequentially supplying fluids including hydrogen peroxide gas to the chamber received by the housing and alternately for evacuating fluids from the chamber to effect sterilization of the articles disposed therein; and means partially disposed within said housing and partially disposed within the chamber for releasably cooperating upon reception of the chamber by the housing to form a fluid passage between the fluid supply and evacuation means and the chamber.

Other details and advantages of the present invention will become apparent from a consideration of the following detailed description, taken with the accompanying drawings.

Brief Description of the Drawings FIG. 1 is a schematic illustration of an application of the method of the present invention; FIG. 2 is a schematic diagram of an application of the method of the present invention in which multiple standardized enclosures are employed; FIG. 3 is an isometric view of a master sterilization unit with cassettes variously positioned with respect thereto; and FIG. 4 is an isometric view of an open cassette of the type shown in Fig. 3, with instruments supported therein.

Detailed Description of the Preferred Embodiments The present invention employs cassette-type contains for housing sterilizable articles during sterilization and thereafter during transport and storage of the sterile articles. The cassette-type containers are self-contained sterilization chambers which, upon being interfaced with a master sterilization unit positioned at a convenient location, receive and vent the necessary fluids required for sterilizing the articles in the chamber and, thereafter, remain hermetically sealed to maintain the contents in a sterile condition until use. The adoption of cassette-type construction for the containers ensures complete portability and reliable interfacing with the master sterilization unit.

Referring to Fig. 1 of the drawings, there is shown a portable cassette generally designated by the reference numeral 1 0. Cassette 10 is formed of any suitable material that can withstand temperatures in ranges up to 1 300F to 1 7O0F and the application of vacuum to the interior of the cassette in the range of 26" of mercury. Cassette 10 further should have insulated properties and have relatively low absorbency to hydrogen peroxide; further, the material of construction should not operate to degrade hydrogen peroxide.

Typical materials of construction are polysulfone and aluminum.

Cassette 10 must be capable of being opened to permit the loading of articles therein; a convenient form of construction is an enclosure having two mating sections joined at one side by hinges 12 and having a locking means 14 disposed opposite hinges 12. The mating surfaces in such case must be adapted to form a complete seal therebetween in accordance with techniques well known in the art. The interior of cassette 10 preferably includes means for supporting the articles to be loaded therein. A cassette embodying these features is illustrated in Fig. 4.

Because cassette 10 is intended to serve both as a sterilizing chamber and later as a storage container for sterile goods, it is fitted with quick disconnect valves 1 6 which interface with corresponding quick disconnect valves 1 8 on a master sterilization unit designated in the drawings by the reference numeral 20. Quick disconnect valves 1 6 provide fluid communication between piping in master sterilization unit 20 and the interior of cassette 10. The structure and operation of quick disconnect valves 1 6 and 18 are well known in the art. The standardization of cassette 10, including the orientation and spacing of quick disconnect valves 16, is desirable so that a variety of different types and sizes of cassettes may interface with a single master sterilization unit 20.

In a typical practice of the method of the present invention, cassette 10 is loaded with items to be sterilized and the cassette is closed and sealed. Cassette 10 then is brought into interfacing relationship with master sterilization unit 20 and quick disconnect valves 1 6 are engaged by their counterparts 1 8 on master sterilization unit 20. In a typical sterilization cycle, air taken in through filter 22 and heated by electrical heater 24 first is passed into cassette 10 through valve 26 and exhausted from cassette 10 through valve 28. The heated air may be recirculated through valve 30 for energy efficiency. The temperature of the heated air circulated within cassette 10 may be in the range of 130 F to 170"F.After the interior of the cassette has reached the desired temperature, air circulation is ceased and a vacuum is drawn on the interior of cassette 10 by means of vacuum pump 30. Hydrogen peroxide gas drawn from a source of hydrogen peroxide 32 is passed through heat exchange unit 34 and valve 36 and thence into the interior of cassette 10. After the sterilizing phase is complete, cassette 10 is again subjected to vacuum and is aerated with filtered sterile air.

Cassette 10 then may be disengaged from master sterilization unit 20; upon disengagement, quick disconnect valves 1 6 operate to seal the interior of cassette 10 from the unsterile surrounding environment. Cassette 10 may be stored for future use of its sterile contents or delivered to a use area for immediate use of the sterile contents.

Referring to Fig. 2, there is shown a master sterilization unit 20 adapted for use with multiple cassettes 40, 42 and 44. With the arrangement shown in Fig. 2, cassettes 40, 42 and 44 may be subjected simultaneously to a single sterilization cycle generated by master sterilization unit 20.

Alternatively, cassettes 40, 42 and 44 may be subjected to individual sequential sterilization cycles controlled by master sterilization unit 20.

From the foregoing it may be seen that the method of the present invention offers considerable flexibility in the number and sizes of cassettes that may be adapted to interface with a single master sterilization unit. This means that cassettes may be specially constructed to house particular items of goods to be sterilized such as uniquely shaped medical or dental instruments.

Further, the method of the present invention offers complete and intimate contact between the gaseous hydrogen peroxide sterilant and the item to be sterilized without concern for whether or not the sterilant penetrates a wrapping material.

Further, the portability of the cassettes permits transportation of the cassettes to and storage at locations remote from the master sterilization unit.

Figs. 3 and 4 illustrate one embodiment of the apparatus of the present invention. Fig. 3 shows master sterilization unit 20 having recesses 50 dimensioned to receive standard size cassettes 10' and 10". Depressible safety switches 52 are arranged in alignment with recesses 50; before cassette 10" could have been inserted into its recess, the corresponding switch 52 had to have been depressed in the manner shown with cassette 10'. Switches 52 operate to prevent operation of a sterilization cycle within master sterilization unit 20 unless a cassette is properly positioned within a recess 50 and also to prevent withdrawal of a cassette before the sterilization cycle is complete.

Claims

1. A method for sterilizing goods in unwrapped condition with hydrogen peroxide gas and thereafter storing said goods in sterile condition without removing them from their sterilizing chamber, comprising the steps of: providing a portable, sealable enclosure for said goods, said enclosure being substantially nonabsorbent to hydrogen peroxide and being capable of withstanding a pressure differential across its walls; loading said goods into said enclosure and sealing it; providing a source of hydrogen peroxide gas; releasably connecting said enclosure to said source of hydrogen peroxide gas to establish fluid communication between said source and the interior of said enclosure; contacting said goods within said enclosure with hydrogen peroxide gas to effect sterilization of said goods; withdrawing said hydrogen peroxide gas from said enclosure;; disengaging said enclosure from said source of hydrogen peroxide gas; and storing said enclosure in a sealed condition until said sterile goods are used.

2. Apparatus for sterilizing articles and maintaining the sterility of said articles during transport and storage, comprising, in combination: a plurality of portable sterilization chambers, each chamber being hermetically sealable and having interiorly disposed means for supporting said articles in spaced-apart relationship; a main housing adapted to receive at least one of said chambers in a fixed orientation for processing; means within said housing for sequentially supplying fluids including hydrogen peroxide gas to said chamber received by said housing and alternately for evacuating fluids from said chamber to effect sterilization of said articles disposed therein; and means partially disposed within said housing and partially disposed within said chamber for releasably cooperating upon reception of a chamber by said housing to form a fluid passage between said fluid supply and evacuation means and said chamber.

3. Apparatus for sterilizing articles and substantially as hereinbefore described and as shown in Figures 3 and 4 of the drawings.