US 2938766 A
Abstract available in
Claims available in
Description (OCR text may contain errors)
United States Patent STERILIZATION (3F HOSPITAL AND PHYSICIANS SUPPLIES Lloyd- A. Hall, Chicago, 111., assignor to The Grifiith Laboratories, Inc, Chicago, 11]., a corporation of Illinois No Drawing. Filed Jan. 21, 1958, Ser. No. 710,198
4 Claims. (Cl. 21 -5.8)
The present invention relates to the sterilization of certain hospital and physicians supplies for the purpose of completely eliminating bacteria, molds and yeasts, and their spores. It is applicable to a wide variety of hospital materials including hemostatic gauze sponges, hemostatic dusting powder, cotton rolls and balls, rolled gauzes, gauze bandages, catgut (animal source) sutures, medicated gelatin films of burns, synthetic sutures, surgical dressings, cotton swab applicators, disposable. diaper liners and diapers, obstetrical pads. for hospital use, nursing pads and other hospital products, many of which items are variously medicated. These are comprehended by the term hospital and physicians supplies of animal and vegetable origin.
In recent years, with the necessity for complete sterilization of various types of supplies used by physicians and hospitals, there has been need for a more rapid process for positive sterilization of these products and in many instances, the old classical method of heat-sterilization in an autoclave has become outmoded. The use of ethylene oxide gas for sterilization has been found to be tremendously effective and satisfactory for the complete elimination of microorganisms and organic life which are always present on or in these materials. It has been found that undiluted ethylene oxide not only is exceed ingly efiicient but also does not contribute toxicity or change in the composition or physical characteristics of the materials herein described.
Since the gas used in the present invention is ethylene oxide gas, certain other standards are applied for the performance of the present invention. It is known that ethylene oxide may be used under conditions to effect a sterile product, but less drastic use thereof may be practiced to produce a product just short of sterile. It is also known that ethylene oxide has insecticidal and bactericidal action and reactivity in the presence of moisture by combining with water to form ethylene glycol, the latter having these properties. Ethylene oxide is reactive with some materials, such as certain proteins, and the present process uses low temperatures to minimize and prevent such reaction. It is known that in using ethylene oxide on dry materials lacking moisture whereby to use the function of ethylene oxide rather than the function of ethylene glycol, that prior processes discharge material with residual traces of ethylene oxide sorbed by the material. Such materials on standing acquire moisture and the residual ethylene oxide reacts therewith to form the glycol, and in some cases reacts with the material involved.
The items to be sterilized in accordance with the present invention may be characterized as merchandise. As such, they are commonly manufactured, processed or packaged at one place, then shipped and stored until use. According to the present invention the materials may be sterilized prior to storage for use. One or more ice gas, so. that a. packed larger container may be. an entity to be subjected to the gas.
Among the materials for the present invention are.
some which are medicated for use, for examples, adhesive tapes, dressings, gauze and swabs. The process is carried out under conditions of low temperature and low moisture content, not only to prevent affecting the medication but also. to minimize or prevent reaction to form ethylene glycol. Although some of the materials contemplated for sterilization may be sterilized without damage by use of temperatures higher than specified, theprocess as a general one' is limited so that mixed. goods of the general class may be sterilized in one operation.
The present invention concerns a sterilizing process wherein the materials in gas-permeable protective containersi are placed in a retort and treated in the following manner:
' (1). Preheat time-from a limit of F. to F. for 45 minutes or longer.
(2) Draw first vacuum to at least 29 inches of mercury and exposed for at least 45 minutes.
(3) Introduce ethylene oxide gas in amount from 30 to 65 pounds per 1000 cu. ft.
(4) Exposure of material to gas from one-half hour to four hours.
(5) Draw second vacuum to at least 29 inches of mercury.
(6) Flush with sterile filtered dry air to attain atmospheric pressure.
(7) Remove the containers.
The process is so effective that the material may be sterilized within containers such as paper bags, fiber drums, cellophane or other plastic film envelopes, corrugated cartons and the like, of course not hermetically sealed. The products are free from a toxic residue of gas and free of ethylene glycol formed from the gas.
The following Table I illustrates the infestation of certain commercial hospital and physicians supplies now available on the market.
(+) Bacterial growth. No bacterial growth. gg riggsed fluid thioglycollate culture medium with incubation After sterilization by the present invention the same materials similarly tested for 14 days show no bacterial growth.
Table H shows the shelf life of certain supplies sterilized by the present invention.
Table 11 Storage in Weeks Material Hemostatlc Gauze Sponges;- Hemostatic Dusting Powden Gauze Bandages. Oatgut Sutures.
' from. a chilled condition of the goods to be sterilized, as
may be encountered in winter; The process is hastened by temperature above 70 'F. but not over 100 F. for preservingthe required character of some items. .The material is thus considered to be activated so that the ethylene oxide can act on the microorganisms probably by increasingthe concentration locally by sudden changes in .the osmotic tension of the organisms so that the gas acts upon 'the cells. The entire process takes approximately four to seven hours in large retorts depending upon the material being treated. i 7
-.I-claim:' a t x 1. The method of sterilizing hospital and physicians supplies of animal and vegetable origin, which comprises subjecting the material enclosed in a gas-permeable protective container therefor. at a temperature in the range from 70 F. to 100 F. to a vacuum of at least 29 inches of mercury in a closed chamber for at least minutes, admitting into said evacuated chamber substantially undiluted ethylene oxide gas in amount in the range from 30 to pounds per 1000 cu. 'ft. of chamber space, thereafter subjecting the material to the action of' said gas for a time in the range from one-half to four hours, then increasing the vacuum to at least 29 inches of mercury and thereby withdrawing free ethylene. oxide gas, then flushing the chamber with sterile filtered dry airrto establish atmospheric pressure in the chamber, and then removing from the chamber the material within its closed gas-permeable container, whereby all of the organic life in the article and within the container is killed.
2; Theprocess of; claim 1 in which the material is cotton.
3. The process of claim 1 in .Which' the material is catgut suture. V r
4. The process of claim 1 in which a plurality of the initial containers are enclosed in a'larger protective gaspermeable container for subjection to said gas, whereby,
the larger container in being shipped or stored provides a supply of' substantially sealed packages of sterilized content. Y x
References Cited in the file of this patent UNITED STATES PATENTS Grifiith Mar. 9, 1943 Baer Ian. 21, 1941 OTHER 7 REFERENCES Phillips: Am. r. of Hygiene, vol. 50, 1949,1111. 210-