Revised guidelines for EO sterilization
The Association for the Advancement of Medical Instrumentation (AAMI) subcommittee on ethylene oxide sterilization, formerly the 279 subcommittee, has released revised guidelines for the use of ethylene oxide sterilization. The original guidelines were published in the June 1974 Journal.' A Jane McCluskey, RN, a member of the AORN Board of Directors and chairman of the AORN Committee, Collaboration with Industry, is a member of the AAMI subcommittee. The committee is chaired by L Rendell-Baker, MD, and R J Fredericks, PhD. Dated July 30, 1976, the paper is as follows. Ethylene Oxide Sterilization A Guide for Hospital Personnel This guide outlines general techniques applicable to all hospital ethylene oxide systems. It is not a substitute for the instructions of the manufacturers of those systems or the Joint Commission on Accreditation of Hospitals (JCAH) infection control standards. Ethylene oxide sterilization is not a substitute for steam sterilization, which should be used whenever possible. 1. Using ethylene oxide Ethylene oxide is a potent sterilizing agent, whether used undiluted or with Freon@,carbon dioxide, or other diluents. Ethylene oxide gas provides an effective sterilant for heat and moisture sensitive items which cannot be steam sterilized. Use of ethylene oxide requires special attention to preparation of materials, wrapping, fulfillment of sterilization cycle parameters, and proper aeration.
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2. Personnel and supervision Hospital personnel operating ethylene oxide equipment must have completed instruction in all parameters of sterilization including aeration procedures. Expert supervision is mandatory. The supervisor must periodically directly observe and document disassembly, cleaning, packaging, sterilization, biological control, and aeration procedures used by hospital personnel on all shifts. Centralized processing and sterilization in hospitals is to be encouraged. 3. Preparation of material Material to be sterilized must be surgically clean. Proteinaceous coatings such as blood or pus protect microorganisms and may prevent sterilization. All materials must be "towel dry." The ethylene oxide sterilization process depends on the presence of adequate but not excessive moisture. Materials must be free from water drops which could interfere with sterilization. Prepared materials must be kept in an area where the relative humidity is 30% or more. Periodic measurement of the relative humidity is important, particularly when the hospital is heated. Never use a hot air oven to force dry materials before wrapping unless such use is approved by the manufacturer of your sterilizer. Remove caps, plugs, valves, or stylettes from devices so that the gas can circulate through them. Hollow bore needles and plastic or rubber tubing must be open at both ends and free from plugs. Disassemble syringes and package them with the plungers outside of the barrels.
AORN Journal, December 1976,Vol24, No 6
4. Wrapping materials Packaging materials enclosing items for sterilization must be highly permeable to ethylene oxide. Suitable wrapping materials include double thickness muslin or paper such as that used for steam sterilization. Several types of heat-sealed plastic and paper pouches and plastic films, eg, polyethylene, are specifically designed for ethylene oxide sterilizers. Consult the instructions of both the packaging manufacturer and sterilizer manufacturer to determine if such wrappings are appropriate for use in your sterilizer. Materials which are inadequately permeable to ethylene oxide and hence must not be used without specific directions to the contrary are: aluminum foil, nylon film, Saran, Nylar, cellophane, and polyamide, polyester, and polyvinylidene films. 5. Loading the sterilizer Load your ethylene oxide sterilizer as you would a steam sterilizer. Allow space between items for circulation of gas in the chamber. Overloading may impede sterilization and must be avoided. Refer to the manufacturer’s instructions concerning specific loading procedures. 6. Sterilization cycles Pay meticulous attention to the manufacturer’s instructions concerning all parameters of sterilization. Successful use of the sterilizer requires particular attention to the time, temperature, gas concentration and humidity requirements of your system. As with steam sterilization, no shortcuts are permissable in sterilization cycles. 7. Biological controls Use a biological monitor which is appropriate for your ethylene oxide system to gain reassurance that sterilizing conditions are being attained. Prepare a test package containing the biological monitor. Wrap the test package with the same wrapping material as the rest of the load. Place the test package in the sterilizer chamber as near as possible to the geometric center of the load. Biological controls should be used frequently to verify the sterilization cycle. Many experts recommend their use in every load. Biological controls must be used in any instance of experimentation, eg, when using new packaging materials.
8. Chemical indicators Simple color change indicators should be used with each package. They show exposure to ethylene oxide gas, but are not intended to replace biological monitors. Do not depend on such indicators to assure that sterilizing conditions were achieved. 9. Aeration following sterilization Adequate aeration is essential following ethylene oxide sterilization of gas absorbent materials such as plastic or rubber items. The ethylene oxide which dissolves in porous materials during the sterilization cycle can, in case of prolonged contact, cause a severe chemical burn. Therefore, all items requiring aeration following sterilization must be prominently identified at the time of packaging. Segregate these items from those composed exclusively of glass and/or metal, and allow adequate aeration time to insure that any remaining ethylene oxide is reduced to a safe level. The actual aeration time required depends on many variables including composition, form and weight of the material sterilized, the type of ethylene oxide sterilization system, and the temperature of aeration. The most common material requiring the longest aeration is polyvinylchloride, otherwise known as vinyl or PVC. When the composition of a device is in doubt, treat it as if it were polyvinylchloride. Follow the aeration cycle procedures that the manufacturer of the sterilizer recommends. The following is an example of aeration instructions for elimination of harmful ethylene oxide residues from the most challenging materials: Room temperature-7 days Elevated temperature in an aeration cabinet at 50 C (122 F)-12 hours Elevated temperature in an aeration cabinet at 60 C (140 F ) - 8 hours Otherwise, consult the manufacturer’s instructions to determine the required aeration time for vinyl and other absorbent materials. When in doubt about aeration requirements for any particular item, follow the recommendation given above. Although aeration of porous materials may be accomplished at ambient (room) temperature, elevated temperature hastens the aeration process. Users should, whenever possible,
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employ a heated mechanical aerator. Items composed exclusively of nonporous material such as metal and glass absorb no ethylene oxide and may be used immediately following sterilization. 10. Precautions Since ethylene oxide is a toxic and flammable material, strict precautions are essential. The ethylene oxide sterilizer must be installed in a well-ventilated room. Vent I
aerators and large sterilizers to the outside atmosphere in accordance with the manufacturer’s instructions. Leave the sterilizer door open for five minutes prior to unloading, to allow residual ethylene oxide in the chamber to dissipate. No smoking may be permitted in the area. Notes 1. Marie G Wisler, “Guidelines for use of ethylene oxide,” AORN Journal 19 (June 1974)
1290-1295.
Surface cooling enables painless skin grafting Surface cooling with ice will produce temporary relief of pain long enough to remove skin grafts without requiring drug anesthesia, it was reported at the annual meeting of the American Society of Anesthesiologists. General anesthesia is commonly used for cutting skin grafts, but there are risks, especially in extensive burns where repeated skin grafting procedures are required. At other times, the low general condition of the patient does not allow use of general anesthesia. Administration of large amounts of local anesthetic can produce adverse reactions. “For these reasons we became interested in using surface cooling to produce a painless area for cutting skin grafts,” said Som N Tandon, MD, and William W Monafo, MD, of the department of plastic surgery, The Christ Hospital, Cincinnati, and the department of surgery, St John’s Mercy Medical Center, St Louis, respectively. Surface cooling is particularly useful when the patient has heart, lung, or kidney problems, in cases of blood poisoning, and in pregnancy. Another advantage is that no fasting is required. “This means that the feeding schedule, important in severely burned patients, may be continued without interruption,” said Dr Tandon. Cooling the skin is carried out by filling a clean plastic bag with crushed ice and firmly wrapping it around the donor area, usually the thigh. “At first there is a feeling of cold in the
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treated area lasting two to three minutes, but the area soon becomes numb,” Dr Tandon explained. “When the ice is removed after 45 to 60 minutes, the numbed area is reddened and stands out from the surrounding skin. The whole thigh or leg may be treated in this manner and skin grafts can readily be cut. The temperature required to produce absence of sensation varies from 41 F to 55.4 F (5 C to 13 C).” No patient had a general feeling of cold or shivering. They did not complain of pain during the postoperative recovery period as the donor area warmed. The donor areas healed in the usual 10 to 14 days. Occasionally, during the graft removal, there is smarting in some areas due to inadequate contact of ice with the skin. In such cases, it was necessary to infiltrate small areas with local anesthetic. The technique was first used in extensive burns where eight to ten operations for skin grafts were needed. Later, its use was extended to patients as young as 1 or 2 years and to patients as old as 92 years who needed skin grafting for minor defects. Surface cooling of the skin with ice or cold water has been known to medicine for many years. Limbs were amputated and wounds were skin grafted by this means during World War II.
AORN Journal, December.1976, Vol 24, N o 6
The Association for the Advancement of Medical Instrumentation (AAMI) subcommittee on ethylene oxide sterilization, formerly the 279 subcommittee, has released revised guidelines for the use of ethylene oxide sterilization. The original guidelines were published in the June 1974 Journal.' A Jane McCluskey, RN, a member of the AORN Board of Directors and chairman of the AORN Committee, Collaboration with Industry, is a member of the AAMI subcommittee. The committee is chaired by L Rendell-Baker, MD, and R J Fredericks, PhD. Dated July 30, 1976, the paper is as follows. Ethylene Oxide Sterilization A Guide for Hospital Personnel This guide outlines general techniques applicable to all hospital ethylene oxide systems. It is not a substitute for the instructions of the manufacturers of those systems or the Joint Commission on Accreditation of Hospitals (JCAH) infection control standards. Ethylene oxide sterilization is not a substitute for steam sterilization, which should be used whenever possible. 1. Using ethylene oxide Ethylene oxide is a potent sterilizing agent, whether used undiluted or with Freon@,carbon dioxide, or other diluents. Ethylene oxide gas provides an effective sterilant for heat and moisture sensitive items which cannot be steam sterilized. Use of ethylene oxide requires special attention to preparation of materials, wrapping, fulfillment of sterilization cycle parameters, and proper aeration.
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2. Personnel and supervision Hospital personnel operating ethylene oxide equipment must have completed instruction in all parameters of sterilization including aeration procedures. Expert supervision is mandatory. The supervisor must periodically directly observe and document disassembly, cleaning, packaging, sterilization, biological control, and aeration procedures used by hospital personnel on all shifts. Centralized processing and sterilization in hospitals is to be encouraged. 3. Preparation of material Material to be sterilized must be surgically clean. Proteinaceous coatings such as blood or pus protect microorganisms and may prevent sterilization. All materials must be "towel dry." The ethylene oxide sterilization process depends on the presence of adequate but not excessive moisture. Materials must be free from water drops which could interfere with sterilization. Prepared materials must be kept in an area where the relative humidity is 30% or more. Periodic measurement of the relative humidity is important, particularly when the hospital is heated. Never use a hot air oven to force dry materials before wrapping unless such use is approved by the manufacturer of your sterilizer. Remove caps, plugs, valves, or stylettes from devices so that the gas can circulate through them. Hollow bore needles and plastic or rubber tubing must be open at both ends and free from plugs. Disassemble syringes and package them with the plungers outside of the barrels.
AORN Journal, December 1976,Vol24, No 6
4. Wrapping materials Packaging materials enclosing items for sterilization must be highly permeable to ethylene oxide. Suitable wrapping materials include double thickness muslin or paper such as that used for steam sterilization. Several types of heat-sealed plastic and paper pouches and plastic films, eg, polyethylene, are specifically designed for ethylene oxide sterilizers. Consult the instructions of both the packaging manufacturer and sterilizer manufacturer to determine if such wrappings are appropriate for use in your sterilizer. Materials which are inadequately permeable to ethylene oxide and hence must not be used without specific directions to the contrary are: aluminum foil, nylon film, Saran, Nylar, cellophane, and polyamide, polyester, and polyvinylidene films. 5. Loading the sterilizer Load your ethylene oxide sterilizer as you would a steam sterilizer. Allow space between items for circulation of gas in the chamber. Overloading may impede sterilization and must be avoided. Refer to the manufacturer’s instructions concerning specific loading procedures. 6. Sterilization cycles Pay meticulous attention to the manufacturer’s instructions concerning all parameters of sterilization. Successful use of the sterilizer requires particular attention to the time, temperature, gas concentration and humidity requirements of your system. As with steam sterilization, no shortcuts are permissable in sterilization cycles. 7. Biological controls Use a biological monitor which is appropriate for your ethylene oxide system to gain reassurance that sterilizing conditions are being attained. Prepare a test package containing the biological monitor. Wrap the test package with the same wrapping material as the rest of the load. Place the test package in the sterilizer chamber as near as possible to the geometric center of the load. Biological controls should be used frequently to verify the sterilization cycle. Many experts recommend their use in every load. Biological controls must be used in any instance of experimentation, eg, when using new packaging materials.
8. Chemical indicators Simple color change indicators should be used with each package. They show exposure to ethylene oxide gas, but are not intended to replace biological monitors. Do not depend on such indicators to assure that sterilizing conditions were achieved. 9. Aeration following sterilization Adequate aeration is essential following ethylene oxide sterilization of gas absorbent materials such as plastic or rubber items. The ethylene oxide which dissolves in porous materials during the sterilization cycle can, in case of prolonged contact, cause a severe chemical burn. Therefore, all items requiring aeration following sterilization must be prominently identified at the time of packaging. Segregate these items from those composed exclusively of glass and/or metal, and allow adequate aeration time to insure that any remaining ethylene oxide is reduced to a safe level. The actual aeration time required depends on many variables including composition, form and weight of the material sterilized, the type of ethylene oxide sterilization system, and the temperature of aeration. The most common material requiring the longest aeration is polyvinylchloride, otherwise known as vinyl or PVC. When the composition of a device is in doubt, treat it as if it were polyvinylchloride. Follow the aeration cycle procedures that the manufacturer of the sterilizer recommends. The following is an example of aeration instructions for elimination of harmful ethylene oxide residues from the most challenging materials: Room temperature-7 days Elevated temperature in an aeration cabinet at 50 C (122 F)-12 hours Elevated temperature in an aeration cabinet at 60 C (140 F ) - 8 hours Otherwise, consult the manufacturer’s instructions to determine the required aeration time for vinyl and other absorbent materials. When in doubt about aeration requirements for any particular item, follow the recommendation given above. Although aeration of porous materials may be accomplished at ambient (room) temperature, elevated temperature hastens the aeration process. Users should, whenever possible,
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employ a heated mechanical aerator. Items composed exclusively of nonporous material such as metal and glass absorb no ethylene oxide and may be used immediately following sterilization. 10. Precautions Since ethylene oxide is a toxic and flammable material, strict precautions are essential. The ethylene oxide sterilizer must be installed in a well-ventilated room. Vent I
aerators and large sterilizers to the outside atmosphere in accordance with the manufacturer’s instructions. Leave the sterilizer door open for five minutes prior to unloading, to allow residual ethylene oxide in the chamber to dissipate. No smoking may be permitted in the area. Notes 1. Marie G Wisler, “Guidelines for use of ethylene oxide,” AORN Journal 19 (June 1974)
1290-1295.
Surface cooling enables painless skin grafting Surface cooling with ice will produce temporary relief of pain long enough to remove skin grafts without requiring drug anesthesia, it was reported at the annual meeting of the American Society of Anesthesiologists. General anesthesia is commonly used for cutting skin grafts, but there are risks, especially in extensive burns where repeated skin grafting procedures are required. At other times, the low general condition of the patient does not allow use of general anesthesia. Administration of large amounts of local anesthetic can produce adverse reactions. “For these reasons we became interested in using surface cooling to produce a painless area for cutting skin grafts,” said Som N Tandon, MD, and William W Monafo, MD, of the department of plastic surgery, The Christ Hospital, Cincinnati, and the department of surgery, St John’s Mercy Medical Center, St Louis, respectively. Surface cooling is particularly useful when the patient has heart, lung, or kidney problems, in cases of blood poisoning, and in pregnancy. Another advantage is that no fasting is required. “This means that the feeding schedule, important in severely burned patients, may be continued without interruption,” said Dr Tandon. Cooling the skin is carried out by filling a clean plastic bag with crushed ice and firmly wrapping it around the donor area, usually the thigh. “At first there is a feeling of cold in the
1088
treated area lasting two to three minutes, but the area soon becomes numb,” Dr Tandon explained. “When the ice is removed after 45 to 60 minutes, the numbed area is reddened and stands out from the surrounding skin. The whole thigh or leg may be treated in this manner and skin grafts can readily be cut. The temperature required to produce absence of sensation varies from 41 F to 55.4 F (5 C to 13 C).” No patient had a general feeling of cold or shivering. They did not complain of pain during the postoperative recovery period as the donor area warmed. The donor areas healed in the usual 10 to 14 days. Occasionally, during the graft removal, there is smarting in some areas due to inadequate contact of ice with the skin. In such cases, it was necessary to infiltrate small areas with local anesthetic. The technique was first used in extensive burns where eight to ten operations for skin grafts were needed. Later, its use was extended to patients as young as 1 or 2 years and to patients as old as 92 years who needed skin grafting for minor defects. Surface cooling of the skin with ice or cold water has been known to medicine for many years. Limbs were amputated and wounds were skin grafted by this means during World War II.
AORN Journal, December.1976, Vol 24, N o 6
