AORN proposed standards for inhospital sterilization
The following draft standards are being published for review and comment from AORN members. The Technical Practices Coordinating Committee (TPCC) of the Association is interested in receiving feedback from the membership regarding content. It should be stressed that AORN technical standards are identified as optimum achievable standards and may not necessarily reflect current practice in each institution. Although comments from nonmembers may be submitted, the intent of the TPCC is a consensus among AORN members. All comments from members will be acknowledged and considered by the TPCC before the final approval of these standards by the AORN Board of Directors. Comments should be sent to: Technical Practices Coordinating Committee AORN Dept S 10170 E Mississippi Ave Denver, Colo 80231 Attn: Janet Schultz Deadline for receipt of comments on these draft standards is June 25. 1979. Purpose: These standards outline procedures used to achieve inhospital sterilization of supplies following terminal decontamination. The success of surgery depends greatly on the creation and maintenance of an aseptic environment. A basic principle of aseptic techniques is that all surgical supplies coming in contact with the surgical field should be sterile. The objective of sterilization is the destruction of all microorganisms by reliable standardized methods using heat, gases,
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chemicals, or radiation. The method of sterilization of surgical instruments, drapes, and other items should be chosen according to the physical and chemical characteristics of the item being sterilized. It should not expose patients or personnel to harmful residues. Standards Standard 1. All articles to be sterilized should be clean and appropriately hydrated. Standard II. Single use items should not be reprocessed. Limited use items should be reprocessed only if the manufacturer provides written recommendations. Interpretive statement A. Written recommendations from the manufacturer include the type of material from which the item is made, the best packaging material to use for reprocessing,the proper method of reprocessing, and aeration instructions. Standard 111. All articles to be sterilized should be prepared so that all surfaces will be directly exposed to the sterilizing agent for the prescribed time and temperature. Interpretive statements A. Packs of gowns or drapes are prepared in a clean environment. Freshly laundered fabrics are used, and packs do not exceed 12 Ibs or dimensions of 12 x 12 x 20 inches. B. When utensils of the same size are nested, they are separated by layers of absorbent towels or other wicking material. All are positioned in the same direction so that if they were filled with water, the liquid would
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run out. C. Instrument sets placed in trays having mesh or perforated bottoms do not exceed 16 Ibs. D. If possible, all jointed instruments are open or unlocked, and instruments composedof more than one part or with sliding parts are disassembled. Instruments are never held tightly together by rubber bands, umbilical tape, or any other means that will prevent steam contact of all surfaces. If lubrication of instruments is necessary, a water soluble lubricant is used. Standard IV. All wrapped articles to be sterilized should be packaged in materials that meet the criteria stated in the AORN Standards for lnhospital Packaging Materials.’ Items other than those in heat-sealed packages should be wrapped sequentially in two wrappers. Interpretive statement A. When nonmuslin wrappers are used in steam sterilization, the time-temperature profile is determined before sterilizing the packages. Standard V. Chemical indicators should be used within and on every package sterilized. Interpretive statements A. An internal chemical indicator that is sensitive to as many physical parameters of sterilization as possible is placed in the center of every package to be sterilized. These physical parameters include time, temperature, and moisture for steam sterilization; and gas concentration for ethylene oxide (EO) sterilization. B. An external chemical indicator, such as heat-sensitive tape, indicating label, or indicating print on packaging material, is clearly visible on every package to be sterilized to show subsequent exposure to sterilization. C. Chemical indicator results are interpreted according to manufacturer’s written instructions. D. Chemical indicators indicate only that the items have been exposed to the physical conditions within a sterilizing chamber.
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They do not replace biological monitoring. Standard VI. Every package intended for sterile use should be imprinted or labeled with a lot control number that indicates the sterilizer used, the cycle or load number, the date of sterilization, and the expiration date. Standard VII. Sterilizers, sterilizing agents, and aerators should be used according to manufacturer’s written instructions. Interpretive statements A. Steam under pressure is the least expensive, safest, and most efficient sterilization method for processing heat- and moisture-stable items. When possible, it should be used in preferenceto all other methods. Ethylene oxide is used for sterilization of heat- and moisture-sensitive items that cannot be steam sterilized. Dry heat is the method of choice for sterilizing anhydrous oils, powders, and petroleum jellies. Cold sterilants are used for heat-sensitive items when ethylene oxide is not available or aeration not practical. B. All articles to be steam sterilized are positioned in the chamber to facilitate free circulation and penetrationof steam, to enhance air elimination, and to prevent entrapment of air or water. C. All articles to be sterilized by ethylene oxide should be positioned in the chamber to facilitate free circulation and penetration of the sterilizing agent. D. All articles sterilized in ethylene oxide are aerated to reduce ethylene oxide residual as well as its byproducts (ethylene glycol and ethylene chlorohydrin) to a safe level before they are handled by any personnel or used in patient care. If articles are wrapped, wrappers are also aerated. Standard VIII. The efficacy of the sterilizing process should be measured at least weekly for steam on the first run of the day and on each load for ethylene oxide. It should be measured by a biological indicator that employs dry spores of a heatresistant species, seeded in known populations on a known surface area and standardized so that a known survival time
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and kill time at a specific temperature or ethylene oxide exposure time can be demonstrated. Interpretive statements A. Bacillus stearothermophilus is used for monitoring s t eam sterilizers. Bacillus subtilis is used for monitoring dry heat and ethylene oxide sterilizers. B. The biological indicator is placed on a pack that is positionedin the front bottom section of a steam-sterilizerload and in the middle section of an ethylene oxide-sterilizer load. C. B stearothermophilus is incubated at 55 C (131 F). Bsubtilis isincubatedat35to37C (95to 98.6 F) or according to manufacturer’s written instructions. D. Where feasible, ethylene oxide-sterilized implantableor intravascular articles are not used until the results of the biological monitoring process are known. E. If a positive biological indicator is reported, the suspect sterilizer is taken out of service until operational maintenance is performed, the sterilizer is retested, and the results of retesting are satisfactory. All items processed in the suspect load are considered unsterile. They are retrieved if possible, washed, repackaged, and resterilized in another sterilizer. F. If a positive biological indicator is obtained, the laboratory will perform a presumptive identificationto determine if the recovered microorganism is the test microorganism that was in the biological indicator or is an accidental contaminant. Standard IX. Sterilized articles should be handledas little as possible with great care and should be stored in a well-ventilated area with controlled temperature and humidity. Interpretive statements A. All wrapped sterilized items remain untouched on the sterilizer rack or carriage for at least 15 minutes following removal from the steam sterilizer or until adequately cooled. B. Closed cabinet storage is preferred to open-shelf storage. If open-shelf storage must be used, the lowest shelf is 8 to 10 inches from the floor and the highest is at
least 18 inches from the ceiling. All shelves are at least 2 inches from outside walls. C. Any sterilized package that is dropped, torn, or has come in contact with wet objects, moisture, or extreme pressure is considered contaminated.
Standard X. Sterilization records for all sterilizers should be maintained and retained for a period of time indicated by the statute of limitations in each state. Interpretive statements A. The process of emergency (flash) sterilization is not addressed in this standard. B. A time-temperature recording chart with the load number of each steam sterilization cycle indicated is maintained and changed daily or more often as required by manufacturer’s instructions. C. A sterilizer record system will contain sterilizer identification number, date of sterilization, cycle number, contents of each lot, duration and temperature of sterilization phase (if not provided on sterilizer recording chart), identification of operator, results of biological tests, timetemperature recording chart from sterilizer, othertest results, and record of repairs and preventive maintenance. Standard XI. The sterilization of supplies should be performed by conscientious, well-trained individuals who demonstrate knowledge of the principles of microbiology as they pertain to the containment of contamination and the sterilization process. Standard XII. Preventive maintenance of all sterilizers should be performed routinely by qualified individualsaccording to hospital policy, using the manufacturer’sservice manual as a guideline. Interpretive statements A. The efficiency and accuracy of monitoring gauges or devices are inspected on a regularly scheduled basis. B. Following any repairs, a test pack containing a biological indicator is run and negative results obtained before the sterilizer is restored to service.
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Guidelines These guidelines present additional information for implementingthe precedingstandards. 1. Reusable linens should be laundered before subsequent sterilization to restore moisture content. 2. The time requiredto achieve sterilization by steam under pressure varies with the method used and the type of item to be sterilized. Time and temperature relationships indicate holding times after the specific temperatures have been reached and do not include heat-up or drying times. a. Using a gravity air removal sterilizer Instruments (metal only) in an unwrapped perforated tray should be exposed to 132 C (270 F) for 3 minutes or 121C (250 F) for 15 minutes. When a high-speed instrument sterilizer is used for emergency sterilization of instruments, steam should be maintained in the sterilizer jacket prior to and during the entire surgical procedure to facilitate rapid attainment of desired temperature. Instruments (metal combined with porous materials) in an unwrapped perforated tray should be exposed to 132 C (270 F) for 10 minutes or 121 C (250 F) for 20 minutes. Instrumentswrapped in the equivalent of four thicknesses of 140thread count muslin should be exposed to 132 C (270 F) for 15 minutes or 121 C (250 F) for 30 minutes. Packs containing drapes, towels, etc should be exposed to 121 C (250 F) for 30 minutes. Bulk loads of wrapped porous and nonporous items (with the exception of rubber gloves and solutions) should be exposed to 121 C (250 F) for 30 minutes. (a) In combined loads, the nonporous items should be placed on the lowest shelves of the steam sterilizer rack or carriage. b. Using a high vacuum sterilizer All porous and nonporous items should be exposed for 4 minutes after the temperature reaches at least 132 C (270 F) at the center of
the packs. (2) A Bowie-Dick type test should be used daily on the first run of the day or at a designated time if sterilizers are used 24 hours a day. After the presterilizationwashing of an item that will be sterilized by ethylene oxide, the item should be wiped or air dried so that no visible water droplets remain. This will reduce the concentration of ethylene glycol formed during sterilization. To sterilize by ethylene oxide, an automated and programmed EO-sterilization process should be used according to the sterilizer manufacturer’s written instructions. a. The sterilizer must provide the correct concentration of sterilant, regulated relative humidity, temperature, and exposure time during the sterilization cycle. b. Sterilizers and aerators should be exhaust ventilated to the outdoors, and the exhaust system should be designed to prevent the entry of ethylene oxide to other work areas and air inlets. Personnel should not work close to the sterilizer during operation. C. Followingthe completion of the sterilization cycle, the sterilizer door should be cracked open approximately 6 inches for 15 minutes before unloading to facilitate dissipation of residual ethylene oxide from the chamber. (1) Personnelshould neither reach into the chamber nor remain close to the sterilizer during this period. d. When the sterilized items are removed from the sterilizer, they should be transferred immediatelyto the aerator or aeration area. e. Following EO sterilization, the length of aeration required depends on the composition and porosity of the sterilized items, the wrap in which the item is sterilized, the concentration of the diluent used with EO for the sterilization process, and the air flow rate and temperature during aeration. (1) Polyvinylchloride (PVC) is one of the most challenging materialsfrom which EO residues must be eliminated. If the composition of an item is not known, it should be treated
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like PVC. Aeration required for PVC in a mechanical aerator with a minimum of 4 air changes per minute is 8 hours at 60 C (140 F) or 12 hours at 50 C (122 F). Aeration time required at ambient room temperature and air circulation is seven days. Ambient aeration should be carried out in a well-ventilated room vented to the outside and restricted to persons normally needed to operate the area. Room temperature should be controlled between 18 and 22 C (65 and 72 F). Items must be protected from moisture, dust, and vermin. Intravenous or irrigation fluids packaged in plastic bags should not be stored in this area. To sterilize by dry heat, minimum timetemperature relationshipsshould be 172 C (340 F) for one hour, 160 C (320 F) for two hours, or 121 C (250 F) for six hours or longer. a. These time-temperature relationships indicate exposure time after the specific temperatures have been reached and do not include heat-up time. b. Overloading the sterilizer should be avoided because it delays heat convection and circulation. To sterilize by cold sterilants, items should be immersed for the length of time recommended by the manufacturer to kill spores. a. Items should be meticulously clean and dry to the point that visible drops of water are absent since the immersion of wet items will dillute the sterilant. b. All surfaces of the items must be in contact with the sterilant. C. Sterilization by cold sterilants should occur immediately prior to use to avoid contamination during the drying period since packaging of these items is difficult. d. Following the period of immersion, items should be rinsed thoroughly with sterile distilled water, placed on a sterile barrier, and dried with a sterile towel. Extreme care should be taken to
minimize the risk of contamination during this procedure. e. Most cold sterilants remain chemically active and stable for a specified period of time. Therefore, it is essential that an expiration date be calculated according to the manufacturer’s written recommendations and marked on the sterilant container.
Rationale 1. All items that enter a surgical wound or body cavity should be sterile. Sterilization kills microorganisms in the vegetative and spore stages. Disinfection kills or inactivates most microorganisms in the vegetative stage, but does not ordinarily kill spores.* 2. Bacterial spores are very resistant to external destructive agent^.^ 3. Saturated steam provides rapid heating and rapid penetrationof textiles or fabrics, destroys all resistant bacterial spores in brief intervalsof exposure, leaves no toxic residue, and is the most economical sterilizing agent4 4. Compared with ethylene oxide sterilization, the risk/benefit ratio of steam sterilization is favored when steam can be used without damaging articles to be sterilized. 5. Bioburden refers to the microbial population present on items or in the environment. When the bioburden is extremely high, a longer exposure to steam or ethyleneoxide may be requiredto achieve effective terminal decontaminati~n.~ 6. Use of freshly laundered fabrics helps prevent superheating, which may cause sterilization failure and shorten life of textiles.6 7. Resterilization and reuse of items intended for single use is potentially hazardous. Many items cannot be thoroughly cleaned after use. Material may deteriorate during resterilization of some items.7 8. Limitingthe size and density of packs aids penetration of steam8 9. The physical conditions necessary for sterilization are difficult to achieve in excessively heavy instrument sets. Heavy sets require an abnormally long time to attain sterilization temperature, and dry-
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ing may be delayed due to condensation and pooling of m o i ~ t u r e . ~ 10. Placing absorbent towels or other wicking material between nested utensils of the same size enhances passage of steam to all surfaces during the sterilization process and facilitates drying.1° 11. Nonmuslin wrappers may have a different time-temperature profile in steam sterilization than muslin wrappers. Steam sterilizer cycles are based on the assumption that packages will be wrapped in 140thread count muslin.ll 12. Chemical indicators provide a check against faulty packaging, loading, or performance of sterilizers.12 13. Proper placement of packs and utensils in a steam sterilizer load facilitates prompt displacement of air, quick contact of steam with all surfaces of containers and contents, and adequate drying. In combined loads of fabrics and hard goods, placing hard goods on the lowest shelves of the sterilizer rack prevents wetting of fabric packs from condensate dripping from hard goods’ surfaces.13 14. When ethylene oxide is absorbed into solids, the process of desorption or elution proceeds very slowly. Residual ethylene oxide and its byproducts are toxic and can cause severe damage to living tissues exposed to them.14 15. The biological monitoring process gives the best indication of the presence or absence of living microorgani~ms.~5 16. Cautious, minimal handling of sterile packages reduces the possibility of microbial recontamination.16 17. Placement of warm, wrapped sterilized items on cold metal shelves can induce condensate formation, resulting in contamination of the items.17 18. Closed cabinets more effectively prevent contamination of sterile packs than open-shelf storage.’* 19. Sterilization by dry heat requires higher temperatures than steam sterilization because death of microorganisms is achieved by oxidation rather than by coagulation of protein, as with moist heat. 20. The Bowie-Dick type test evaluates ability of prevacuum sterilizers to reduce effec-
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tively air residuals from the chamber space to prevent air reentrainment into the load and to detect the presence of air leaks.20 Notes 1. “Standards for inhospitalpackaging material,” AORN Journal 23 (May 1976)978-979. 2. Seymour S Block, “Definition of terms,” in Dis-
infection, Sterilization, and Preservation, 2nd ed, edited by Seymour S Block (Philadelphia: Lea & Febiger, 1977) 1025-1028. 3. Aram Beloian, “Methods of testing for sterillty and efficacy of sterilizers, sporicides, and sterilizing processes,” in Disinfection, Sterilization, and Presewation, 2nd ed, edited by Seymour S Block (Philadelphia: Lea & Febiger, 1977) 1 1 ; Bertha Y Litsky, “Microbiology of sterilization,” AORN Journal 26 (August 1977)334-350. 4. John J Perkins, Principles and Methods of Sterilization in HealthSciences, 2nd ed (Springfield, 111: Charles C Thomas, 1969)95. 5. Litsky, “Microbiology of sterilization,” 334-350. 6. Perkins, Principles and Methods of Sterilization, 213-214. 7. Carl W Bruch, “Safety aspectsof resterilization of single-use and disposable devices by hospitals,” Willson J Respiratory Care 19 (May 1974)354-360; Fahlberg, “The hospital (disposable) environment,” in IndustrialSterilization, edited by G Briggs Phillips, William S Miller (Durham, NC: Duke University Press, 1973) 399-412;Association for the Advancement of Medical Instrumentation, “FDA resterilization policy,” AAMl News 12 (DecemberJanuary 1978); Bertil Nystrom, “Handling sterile products in the hospital,” in Industrial Sterilization, edited by G Briggs Phillips, William S Miller (Durham, NC: Duke University Press, 1973) 359370. 8. Perkins, Principles and Methods of Sterilization, 195. 9. Association for the Advancement of Medical Instrumentation, “Steam sterilization and sterility assurance-good hospital practice,” Arlington, VA 1979. 10. Perkins, Principles and Methods of Sterilization, 260. 11. Bertha Y Litsky, Warren Litsky, “Standards for packaging needed for improved safety,” AORN Journal 23 (January 1976)27-28;Bertha Y Litsky, Warren Litsky, “Thermocouple pyrometer data for evaluating inhospital packaging material,” AORN Journal 23 (June 1976) 1 175-1176. 12. Perkins,Principles and Methods of Sterilization, 488. 13. Robert R Ernst, “Sterilization by heat,” in Disinfection, Sterilization, and Preservation, 2nd ed, edited by Seymour S Block (Philadelphia: Lea 8,
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Febiger, 1977) 518; Perkins, Principles and Methods of Sterilization, 231. 14. Association for the Advancement of Medical Instrumentation,Subcommittee on Ethylene Oxide Sterilization, “Revised guidelines for EO sterilization,” AORN Journal 24 (December 1976) 10861088; Leslie Rendell-Baker,Robert B Roberts, “Gas versus steam sterilization: When to use which,” Hospital Topics 48 (November 1970) 81-86. 15. Perkins, Principles and Methods of Sterilization, 493. 16. George F Mallison, Paul G Standard, “Safe storage times for sterile packs,” Hospitals 48 (Oct 16, 1974) 77-80. 17. Perkins, Principles and Methods of Sterilization, 219. 18. Mallison, Standard, “Safe storage times,’’ 77-80. 19. Ernst, “Sterilization by heat,” 210. 20. Association for the Advancement of Medical Instrumentation, “Steam sterilization and sterility assurance;” Ernst, “Sterilization by heat,” 500-501. Suggested readings American Hospital Association, American Society for HospitalCentral Service Personnel. “Optimum guidelines for central service.” Chicago, 1977. Association for the Advancement of Medical Instrumentation, Sterilization Standards Committee, Biological Indicator Subcommittee. “Biological indicator-evaluatorresistometer steam vessel standard, (proposed).” Arlington, Va, 1978. Borick, Paul M, ed. Chemical Sterilization. Stroudsburg, Pa: Dowden, Hutchinson & Ross, 1973. Bruch, Carl W. “Factors determining choice of sterilization procedure,” in lndustrial Sterilization. Edited by G Briggs Phillips, William S Miller. Durham, NC: Duke University Press, 1973. Canadian Standards Association. “Effective steam sterilization in hospitals by the steam process,” Draft 2314.3. Rexdale, Ontario, December 1977. “Food and Drug Administrationissues guidelinesfor ethylene oxide sterilization.” Hospitals 49 (Nov 16, 1975) 81-82. Ginsberg, Frances; Clarke, Barbara. “Biological monitor is best test of EtO sterilizer.” Modern Hospital 121 (August 1973) 92. Great Plains Society for Hospital Central Service Personneland Kansas HospitalAssociation.“Optimum objectives for central service.” Topeka, Kan, March 1977. Joint Commission on Accreditation of Hospitals. “Standards for infection control,” in Accreditation Manualfor Hospitals. Chicago: Joint Commission on Accreditation of Hospitals, February 1976. Litsky, Bertha Y. “Sterility assurance inhospitalwho’s responsible?”AORN Journal 27 (February 1978) 200-201.
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Macek, Thomas J. “Biological indicators and the effectiveness of sterilization procedures,” in lndustrial Sterilization. Edited by G Briggs Phillips, William S Miller. Durham, NC: Duke University Press, 1973. Matsumoto, T; Hardaway, R M; Pani, K C; Sater, C M; Bartek, D E; Margetis, P M. “Safe standards of aeration for ethylene oxide sterilized supplies.” Archives of Surgery 96 (1968) 464-470. Nichols, Glennadee; Dobek, Arthur S. “Sterility of items sealed in plastic.” Hospital Topics 49 (December 1971) 77-79. Ryan, Peggy. “Inhospital packaging rationale.” AORN Journal 23 (May 1976) 980-988. US Department of Air Force, Medical Service. Central Supply Service, AFM 106-1976.Washington, DC: Department of Air Force, 1976. US Department of Army. Medical Services Sterilizing: Medical, Surgical, and Dental Material, AR 40-19. Washington, DC: Department of Army, April 1972. US Veterans Administration. “Planning criteria for medicalfacilities,” in Departmentof Medicine and Surgery Manual, H-08-9. Washington, DC: Veterans Administration, March 1974. US Veterans Administration. “Supply processing and distribution operational requirements,” in Manual MP-2, subchapter E, Part 108-76, Washington, DC: Veterans Administration.
Publication details sources of sodium A guide to the amounts of sodium contained in various foods and beverages has been published by the Water Quality Association. The publication, Sources of Sodium in the Diet, has tables that list the sodium content of nearly 200 common foods. There is also a listing of the sodium content of both hard and softened water in 100 US cities and a comparison of the amounts of sodium contained in water, soft drinks, milk, wine, and beer. A section discusses health implications of salt consumption. Characteristics and possible effects of drinking artificially softened water are compared in detail with the effects of the minerals, including cadmium, contained in naturally hard water. The publication is available for $1 from the Water Quality Association, 477 E Butterfield Rd, Lombard, 111 60148.
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The following draft standards are being published for review and comment from AORN members. The Technical Practices Coordinating Committee (TPCC) of the Association is interested in receiving feedback from the membership regarding content. It should be stressed that AORN technical standards are identified as optimum achievable standards and may not necessarily reflect current practice in each institution. Although comments from nonmembers may be submitted, the intent of the TPCC is a consensus among AORN members. All comments from members will be acknowledged and considered by the TPCC before the final approval of these standards by the AORN Board of Directors. Comments should be sent to: Technical Practices Coordinating Committee AORN Dept S 10170 E Mississippi Ave Denver, Colo 80231 Attn: Janet Schultz Deadline for receipt of comments on these draft standards is June 25. 1979. Purpose: These standards outline procedures used to achieve inhospital sterilization of supplies following terminal decontamination. The success of surgery depends greatly on the creation and maintenance of an aseptic environment. A basic principle of aseptic techniques is that all surgical supplies coming in contact with the surgical field should be sterile. The objective of sterilization is the destruction of all microorganisms by reliable standardized methods using heat, gases,
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chemicals, or radiation. The method of sterilization of surgical instruments, drapes, and other items should be chosen according to the physical and chemical characteristics of the item being sterilized. It should not expose patients or personnel to harmful residues. Standards Standard 1. All articles to be sterilized should be clean and appropriately hydrated. Standard II. Single use items should not be reprocessed. Limited use items should be reprocessed only if the manufacturer provides written recommendations. Interpretive statement A. Written recommendations from the manufacturer include the type of material from which the item is made, the best packaging material to use for reprocessing,the proper method of reprocessing, and aeration instructions. Standard 111. All articles to be sterilized should be prepared so that all surfaces will be directly exposed to the sterilizing agent for the prescribed time and temperature. Interpretive statements A. Packs of gowns or drapes are prepared in a clean environment. Freshly laundered fabrics are used, and packs do not exceed 12 Ibs or dimensions of 12 x 12 x 20 inches. B. When utensils of the same size are nested, they are separated by layers of absorbent towels or other wicking material. All are positioned in the same direction so that if they were filled with water, the liquid would
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run out. C. Instrument sets placed in trays having mesh or perforated bottoms do not exceed 16 Ibs. D. If possible, all jointed instruments are open or unlocked, and instruments composedof more than one part or with sliding parts are disassembled. Instruments are never held tightly together by rubber bands, umbilical tape, or any other means that will prevent steam contact of all surfaces. If lubrication of instruments is necessary, a water soluble lubricant is used. Standard IV. All wrapped articles to be sterilized should be packaged in materials that meet the criteria stated in the AORN Standards for lnhospital Packaging Materials.’ Items other than those in heat-sealed packages should be wrapped sequentially in two wrappers. Interpretive statement A. When nonmuslin wrappers are used in steam sterilization, the time-temperature profile is determined before sterilizing the packages. Standard V. Chemical indicators should be used within and on every package sterilized. Interpretive statements A. An internal chemical indicator that is sensitive to as many physical parameters of sterilization as possible is placed in the center of every package to be sterilized. These physical parameters include time, temperature, and moisture for steam sterilization; and gas concentration for ethylene oxide (EO) sterilization. B. An external chemical indicator, such as heat-sensitive tape, indicating label, or indicating print on packaging material, is clearly visible on every package to be sterilized to show subsequent exposure to sterilization. C. Chemical indicator results are interpreted according to manufacturer’s written instructions. D. Chemical indicators indicate only that the items have been exposed to the physical conditions within a sterilizing chamber.
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They do not replace biological monitoring. Standard VI. Every package intended for sterile use should be imprinted or labeled with a lot control number that indicates the sterilizer used, the cycle or load number, the date of sterilization, and the expiration date. Standard VII. Sterilizers, sterilizing agents, and aerators should be used according to manufacturer’s written instructions. Interpretive statements A. Steam under pressure is the least expensive, safest, and most efficient sterilization method for processing heat- and moisture-stable items. When possible, it should be used in preferenceto all other methods. Ethylene oxide is used for sterilization of heat- and moisture-sensitive items that cannot be steam sterilized. Dry heat is the method of choice for sterilizing anhydrous oils, powders, and petroleum jellies. Cold sterilants are used for heat-sensitive items when ethylene oxide is not available or aeration not practical. B. All articles to be steam sterilized are positioned in the chamber to facilitate free circulation and penetrationof steam, to enhance air elimination, and to prevent entrapment of air or water. C. All articles to be sterilized by ethylene oxide should be positioned in the chamber to facilitate free circulation and penetration of the sterilizing agent. D. All articles sterilized in ethylene oxide are aerated to reduce ethylene oxide residual as well as its byproducts (ethylene glycol and ethylene chlorohydrin) to a safe level before they are handled by any personnel or used in patient care. If articles are wrapped, wrappers are also aerated. Standard VIII. The efficacy of the sterilizing process should be measured at least weekly for steam on the first run of the day and on each load for ethylene oxide. It should be measured by a biological indicator that employs dry spores of a heatresistant species, seeded in known populations on a known surface area and standardized so that a known survival time
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and kill time at a specific temperature or ethylene oxide exposure time can be demonstrated. Interpretive statements A. Bacillus stearothermophilus is used for monitoring s t eam sterilizers. Bacillus subtilis is used for monitoring dry heat and ethylene oxide sterilizers. B. The biological indicator is placed on a pack that is positionedin the front bottom section of a steam-sterilizerload and in the middle section of an ethylene oxide-sterilizer load. C. B stearothermophilus is incubated at 55 C (131 F). Bsubtilis isincubatedat35to37C (95to 98.6 F) or according to manufacturer’s written instructions. D. Where feasible, ethylene oxide-sterilized implantableor intravascular articles are not used until the results of the biological monitoring process are known. E. If a positive biological indicator is reported, the suspect sterilizer is taken out of service until operational maintenance is performed, the sterilizer is retested, and the results of retesting are satisfactory. All items processed in the suspect load are considered unsterile. They are retrieved if possible, washed, repackaged, and resterilized in another sterilizer. F. If a positive biological indicator is obtained, the laboratory will perform a presumptive identificationto determine if the recovered microorganism is the test microorganism that was in the biological indicator or is an accidental contaminant. Standard IX. Sterilized articles should be handledas little as possible with great care and should be stored in a well-ventilated area with controlled temperature and humidity. Interpretive statements A. All wrapped sterilized items remain untouched on the sterilizer rack or carriage for at least 15 minutes following removal from the steam sterilizer or until adequately cooled. B. Closed cabinet storage is preferred to open-shelf storage. If open-shelf storage must be used, the lowest shelf is 8 to 10 inches from the floor and the highest is at
least 18 inches from the ceiling. All shelves are at least 2 inches from outside walls. C. Any sterilized package that is dropped, torn, or has come in contact with wet objects, moisture, or extreme pressure is considered contaminated.
Standard X. Sterilization records for all sterilizers should be maintained and retained for a period of time indicated by the statute of limitations in each state. Interpretive statements A. The process of emergency (flash) sterilization is not addressed in this standard. B. A time-temperature recording chart with the load number of each steam sterilization cycle indicated is maintained and changed daily or more often as required by manufacturer’s instructions. C. A sterilizer record system will contain sterilizer identification number, date of sterilization, cycle number, contents of each lot, duration and temperature of sterilization phase (if not provided on sterilizer recording chart), identification of operator, results of biological tests, timetemperature recording chart from sterilizer, othertest results, and record of repairs and preventive maintenance. Standard XI. The sterilization of supplies should be performed by conscientious, well-trained individuals who demonstrate knowledge of the principles of microbiology as they pertain to the containment of contamination and the sterilization process. Standard XII. Preventive maintenance of all sterilizers should be performed routinely by qualified individualsaccording to hospital policy, using the manufacturer’sservice manual as a guideline. Interpretive statements A. The efficiency and accuracy of monitoring gauges or devices are inspected on a regularly scheduled basis. B. Following any repairs, a test pack containing a biological indicator is run and negative results obtained before the sterilizer is restored to service.
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Guidelines These guidelines present additional information for implementingthe precedingstandards. 1. Reusable linens should be laundered before subsequent sterilization to restore moisture content. 2. The time requiredto achieve sterilization by steam under pressure varies with the method used and the type of item to be sterilized. Time and temperature relationships indicate holding times after the specific temperatures have been reached and do not include heat-up or drying times. a. Using a gravity air removal sterilizer Instruments (metal only) in an unwrapped perforated tray should be exposed to 132 C (270 F) for 3 minutes or 121C (250 F) for 15 minutes. When a high-speed instrument sterilizer is used for emergency sterilization of instruments, steam should be maintained in the sterilizer jacket prior to and during the entire surgical procedure to facilitate rapid attainment of desired temperature. Instruments (metal combined with porous materials) in an unwrapped perforated tray should be exposed to 132 C (270 F) for 10 minutes or 121 C (250 F) for 20 minutes. Instrumentswrapped in the equivalent of four thicknesses of 140thread count muslin should be exposed to 132 C (270 F) for 15 minutes or 121 C (250 F) for 30 minutes. Packs containing drapes, towels, etc should be exposed to 121 C (250 F) for 30 minutes. Bulk loads of wrapped porous and nonporous items (with the exception of rubber gloves and solutions) should be exposed to 121 C (250 F) for 30 minutes. (a) In combined loads, the nonporous items should be placed on the lowest shelves of the steam sterilizer rack or carriage. b. Using a high vacuum sterilizer All porous and nonporous items should be exposed for 4 minutes after the temperature reaches at least 132 C (270 F) at the center of
the packs. (2) A Bowie-Dick type test should be used daily on the first run of the day or at a designated time if sterilizers are used 24 hours a day. After the presterilizationwashing of an item that will be sterilized by ethylene oxide, the item should be wiped or air dried so that no visible water droplets remain. This will reduce the concentration of ethylene glycol formed during sterilization. To sterilize by ethylene oxide, an automated and programmed EO-sterilization process should be used according to the sterilizer manufacturer’s written instructions. a. The sterilizer must provide the correct concentration of sterilant, regulated relative humidity, temperature, and exposure time during the sterilization cycle. b. Sterilizers and aerators should be exhaust ventilated to the outdoors, and the exhaust system should be designed to prevent the entry of ethylene oxide to other work areas and air inlets. Personnel should not work close to the sterilizer during operation. C. Followingthe completion of the sterilization cycle, the sterilizer door should be cracked open approximately 6 inches for 15 minutes before unloading to facilitate dissipation of residual ethylene oxide from the chamber. (1) Personnelshould neither reach into the chamber nor remain close to the sterilizer during this period. d. When the sterilized items are removed from the sterilizer, they should be transferred immediatelyto the aerator or aeration area. e. Following EO sterilization, the length of aeration required depends on the composition and porosity of the sterilized items, the wrap in which the item is sterilized, the concentration of the diluent used with EO for the sterilization process, and the air flow rate and temperature during aeration. (1) Polyvinylchloride (PVC) is one of the most challenging materialsfrom which EO residues must be eliminated. If the composition of an item is not known, it should be treated
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like PVC. Aeration required for PVC in a mechanical aerator with a minimum of 4 air changes per minute is 8 hours at 60 C (140 F) or 12 hours at 50 C (122 F). Aeration time required at ambient room temperature and air circulation is seven days. Ambient aeration should be carried out in a well-ventilated room vented to the outside and restricted to persons normally needed to operate the area. Room temperature should be controlled between 18 and 22 C (65 and 72 F). Items must be protected from moisture, dust, and vermin. Intravenous or irrigation fluids packaged in plastic bags should not be stored in this area. To sterilize by dry heat, minimum timetemperature relationshipsshould be 172 C (340 F) for one hour, 160 C (320 F) for two hours, or 121 C (250 F) for six hours or longer. a. These time-temperature relationships indicate exposure time after the specific temperatures have been reached and do not include heat-up time. b. Overloading the sterilizer should be avoided because it delays heat convection and circulation. To sterilize by cold sterilants, items should be immersed for the length of time recommended by the manufacturer to kill spores. a. Items should be meticulously clean and dry to the point that visible drops of water are absent since the immersion of wet items will dillute the sterilant. b. All surfaces of the items must be in contact with the sterilant. C. Sterilization by cold sterilants should occur immediately prior to use to avoid contamination during the drying period since packaging of these items is difficult. d. Following the period of immersion, items should be rinsed thoroughly with sterile distilled water, placed on a sterile barrier, and dried with a sterile towel. Extreme care should be taken to
minimize the risk of contamination during this procedure. e. Most cold sterilants remain chemically active and stable for a specified period of time. Therefore, it is essential that an expiration date be calculated according to the manufacturer’s written recommendations and marked on the sterilant container.
Rationale 1. All items that enter a surgical wound or body cavity should be sterile. Sterilization kills microorganisms in the vegetative and spore stages. Disinfection kills or inactivates most microorganisms in the vegetative stage, but does not ordinarily kill spores.* 2. Bacterial spores are very resistant to external destructive agent^.^ 3. Saturated steam provides rapid heating and rapid penetrationof textiles or fabrics, destroys all resistant bacterial spores in brief intervalsof exposure, leaves no toxic residue, and is the most economical sterilizing agent4 4. Compared with ethylene oxide sterilization, the risk/benefit ratio of steam sterilization is favored when steam can be used without damaging articles to be sterilized. 5. Bioburden refers to the microbial population present on items or in the environment. When the bioburden is extremely high, a longer exposure to steam or ethyleneoxide may be requiredto achieve effective terminal decontaminati~n.~ 6. Use of freshly laundered fabrics helps prevent superheating, which may cause sterilization failure and shorten life of textiles.6 7. Resterilization and reuse of items intended for single use is potentially hazardous. Many items cannot be thoroughly cleaned after use. Material may deteriorate during resterilization of some items.7 8. Limitingthe size and density of packs aids penetration of steam8 9. The physical conditions necessary for sterilization are difficult to achieve in excessively heavy instrument sets. Heavy sets require an abnormally long time to attain sterilization temperature, and dry-
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ing may be delayed due to condensation and pooling of m o i ~ t u r e . ~ 10. Placing absorbent towels or other wicking material between nested utensils of the same size enhances passage of steam to all surfaces during the sterilization process and facilitates drying.1° 11. Nonmuslin wrappers may have a different time-temperature profile in steam sterilization than muslin wrappers. Steam sterilizer cycles are based on the assumption that packages will be wrapped in 140thread count muslin.ll 12. Chemical indicators provide a check against faulty packaging, loading, or performance of sterilizers.12 13. Proper placement of packs and utensils in a steam sterilizer load facilitates prompt displacement of air, quick contact of steam with all surfaces of containers and contents, and adequate drying. In combined loads of fabrics and hard goods, placing hard goods on the lowest shelves of the sterilizer rack prevents wetting of fabric packs from condensate dripping from hard goods’ surfaces.13 14. When ethylene oxide is absorbed into solids, the process of desorption or elution proceeds very slowly. Residual ethylene oxide and its byproducts are toxic and can cause severe damage to living tissues exposed to them.14 15. The biological monitoring process gives the best indication of the presence or absence of living microorgani~ms.~5 16. Cautious, minimal handling of sterile packages reduces the possibility of microbial recontamination.16 17. Placement of warm, wrapped sterilized items on cold metal shelves can induce condensate formation, resulting in contamination of the items.17 18. Closed cabinets more effectively prevent contamination of sterile packs than open-shelf storage.’* 19. Sterilization by dry heat requires higher temperatures than steam sterilization because death of microorganisms is achieved by oxidation rather than by coagulation of protein, as with moist heat. 20. The Bowie-Dick type test evaluates ability of prevacuum sterilizers to reduce effec-
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tively air residuals from the chamber space to prevent air reentrainment into the load and to detect the presence of air leaks.20 Notes 1. “Standards for inhospitalpackaging material,” AORN Journal 23 (May 1976)978-979. 2. Seymour S Block, “Definition of terms,” in Dis-
infection, Sterilization, and Preservation, 2nd ed, edited by Seymour S Block (Philadelphia: Lea & Febiger, 1977) 1025-1028. 3. Aram Beloian, “Methods of testing for sterillty and efficacy of sterilizers, sporicides, and sterilizing processes,” in Disinfection, Sterilization, and Presewation, 2nd ed, edited by Seymour S Block (Philadelphia: Lea & Febiger, 1977) 1 1 ; Bertha Y Litsky, “Microbiology of sterilization,” AORN Journal 26 (August 1977)334-350. 4. John J Perkins, Principles and Methods of Sterilization in HealthSciences, 2nd ed (Springfield, 111: Charles C Thomas, 1969)95. 5. Litsky, “Microbiology of sterilization,” 334-350. 6. Perkins, Principles and Methods of Sterilization, 213-214. 7. Carl W Bruch, “Safety aspectsof resterilization of single-use and disposable devices by hospitals,” Willson J Respiratory Care 19 (May 1974)354-360; Fahlberg, “The hospital (disposable) environment,” in IndustrialSterilization, edited by G Briggs Phillips, William S Miller (Durham, NC: Duke University Press, 1973) 399-412;Association for the Advancement of Medical Instrumentation, “FDA resterilization policy,” AAMl News 12 (DecemberJanuary 1978); Bertil Nystrom, “Handling sterile products in the hospital,” in Industrial Sterilization, edited by G Briggs Phillips, William S Miller (Durham, NC: Duke University Press, 1973) 359370. 8. Perkins, Principles and Methods of Sterilization, 195. 9. Association for the Advancement of Medical Instrumentation, “Steam sterilization and sterility assurance-good hospital practice,” Arlington, VA 1979. 10. Perkins, Principles and Methods of Sterilization, 260. 11. Bertha Y Litsky, Warren Litsky, “Standards for packaging needed for improved safety,” AORN Journal 23 (January 1976)27-28;Bertha Y Litsky, Warren Litsky, “Thermocouple pyrometer data for evaluating inhospital packaging material,” AORN Journal 23 (June 1976) 1 175-1176. 12. Perkins,Principles and Methods of Sterilization, 488. 13. Robert R Ernst, “Sterilization by heat,” in Disinfection, Sterilization, and Preservation, 2nd ed, edited by Seymour S Block (Philadelphia: Lea 8,
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Febiger, 1977) 518; Perkins, Principles and Methods of Sterilization, 231. 14. Association for the Advancement of Medical Instrumentation,Subcommittee on Ethylene Oxide Sterilization, “Revised guidelines for EO sterilization,” AORN Journal 24 (December 1976) 10861088; Leslie Rendell-Baker,Robert B Roberts, “Gas versus steam sterilization: When to use which,” Hospital Topics 48 (November 1970) 81-86. 15. Perkins, Principles and Methods of Sterilization, 493. 16. George F Mallison, Paul G Standard, “Safe storage times for sterile packs,” Hospitals 48 (Oct 16, 1974) 77-80. 17. Perkins, Principles and Methods of Sterilization, 219. 18. Mallison, Standard, “Safe storage times,’’ 77-80. 19. Ernst, “Sterilization by heat,” 210. 20. Association for the Advancement of Medical Instrumentation, “Steam sterilization and sterility assurance;” Ernst, “Sterilization by heat,” 500-501. Suggested readings American Hospital Association, American Society for HospitalCentral Service Personnel. “Optimum guidelines for central service.” Chicago, 1977. Association for the Advancement of Medical Instrumentation, Sterilization Standards Committee, Biological Indicator Subcommittee. “Biological indicator-evaluatorresistometer steam vessel standard, (proposed).” Arlington, Va, 1978. Borick, Paul M, ed. Chemical Sterilization. Stroudsburg, Pa: Dowden, Hutchinson & Ross, 1973. Bruch, Carl W. “Factors determining choice of sterilization procedure,” in lndustrial Sterilization. Edited by G Briggs Phillips, William S Miller. Durham, NC: Duke University Press, 1973. Canadian Standards Association. “Effective steam sterilization in hospitals by the steam process,” Draft 2314.3. Rexdale, Ontario, December 1977. “Food and Drug Administrationissues guidelinesfor ethylene oxide sterilization.” Hospitals 49 (Nov 16, 1975) 81-82. Ginsberg, Frances; Clarke, Barbara. “Biological monitor is best test of EtO sterilizer.” Modern Hospital 121 (August 1973) 92. Great Plains Society for Hospital Central Service Personneland Kansas HospitalAssociation.“Optimum objectives for central service.” Topeka, Kan, March 1977. Joint Commission on Accreditation of Hospitals. “Standards for infection control,” in Accreditation Manualfor Hospitals. Chicago: Joint Commission on Accreditation of Hospitals, February 1976. Litsky, Bertha Y. “Sterility assurance inhospitalwho’s responsible?”AORN Journal 27 (February 1978) 200-201.
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Macek, Thomas J. “Biological indicators and the effectiveness of sterilization procedures,” in lndustrial Sterilization. Edited by G Briggs Phillips, William S Miller. Durham, NC: Duke University Press, 1973. Matsumoto, T; Hardaway, R M; Pani, K C; Sater, C M; Bartek, D E; Margetis, P M. “Safe standards of aeration for ethylene oxide sterilized supplies.” Archives of Surgery 96 (1968) 464-470. Nichols, Glennadee; Dobek, Arthur S. “Sterility of items sealed in plastic.” Hospital Topics 49 (December 1971) 77-79. Ryan, Peggy. “Inhospital packaging rationale.” AORN Journal 23 (May 1976) 980-988. US Department of Air Force, Medical Service. Central Supply Service, AFM 106-1976.Washington, DC: Department of Air Force, 1976. US Department of Army. Medical Services Sterilizing: Medical, Surgical, and Dental Material, AR 40-19. Washington, DC: Department of Army, April 1972. US Veterans Administration. “Planning criteria for medicalfacilities,” in Departmentof Medicine and Surgery Manual, H-08-9. Washington, DC: Veterans Administration, March 1974. US Veterans Administration. “Supply processing and distribution operational requirements,” in Manual MP-2, subchapter E, Part 108-76, Washington, DC: Veterans Administration.
Publication details sources of sodium A guide to the amounts of sodium contained in various foods and beverages has been published by the Water Quality Association. The publication, Sources of Sodium in the Diet, has tables that list the sodium content of nearly 200 common foods. There is also a listing of the sodium content of both hard and softened water in 100 US cities and a comparison of the amounts of sodium contained in water, soft drinks, milk, wine, and beer. A section discusses health implications of salt consumption. Characteristics and possible effects of drinking artificially softened water are compared in detail with the effects of the minerals, including cadmium, contained in naturally hard water. The publication is available for $1 from the Water Quality Association, 477 E Butterfield Rd, Lombard, 111 60148.
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