Assuring Sterility in Surgical Instruments ReprocessingBy Adebusola Owokole, Founder/President, The Operating Room Global (TORG).https://www.operatingroomissues.org/March, 2021OVERVIEW: The delivery of sterile surgical instruments for use inpatient care depends not only on the effectiveness of the sterilizationprocess but also on the unit design, decontamination, disassemblingand packaging of the device, loading the sterilizer, monitoring, sterilantquality and quantity, and the appropriateness of the cycle for the loadcontents, and other aspects of device reprocessing. Sterility assurancelevel (SAL) is the probability that a single microbe would remain onan instrument after sterilization and is a cornerstone of a successfulinfection prevention program. An effective sterilization protocol willhelp ensure the delivery of safe care.CLEANING: The first critical step to sterility assurance in reprocessingis cleaning. Before instruments can be sterilized, they must be free ofbioburden and foreign material i.e., organic residue and inorganic saltsthat interfere with the sterilization process by acting as a barrier to thesterilization agent. Bioburden and debris can impede the sterilant fromreaching the surface. If cement is discovered on a surgical instrumentthat has been reprocessed, removing the cement can expose a surfacethat steam did not reach, and viable microorganisms could exist.Several types of automated mechanical cleaning machines e.g., utensilwasher-sanitizer, ultrasonic cleaner, washer-sterilizer, dishwasher,washer-disinfector may facilitate cleaning and decontamination of mostitems. This increases productivity, improves cleaning effectiveness,and decreases worker exposure to blood and body fluids. Delicate andintricate objects and heat- or moisture-sensitive articles may requirecareful cleaning by hand.STERILIZATION CYCLE VERIFICATION: Sterilization process is verifiedby running three consecutive empty steam cycles with a biological andchemical indicator in an appropriate test package or tray, or with aBowie-Dick test in a pre-vacuum steam sterilizer. Each type of steamcycle used for sterilization (e.g., vacuum-assisted, gravity) is testedseparately. The sterilizer is not put back into use until all biologicalindicators are negative and chemical indicators show a correct endpointresponse. Once the cycle is complete, physical monitors oftime, temperature and pressure provide a real-time evaluation of thesterilization process.PHYSICAL FACILITIES: The central processing area(s) ideally shouldbe divided into at least three areas: decontamination, packaging,and sterilization and storage. Physical barriers should separate thedecontamination area from the other sections to contain contaminationon used items. The recommended airflow pattern should containcontaminates within the decontamination area and minimize the flowof contaminates to the clean areas. The sterile storage area should bea limited access area with a controlled temperature (may be as high as75°F) and relative humidity (30-60% in all works areas except sterilestorage, where the relative humidity should not exceed 70%).PACKAGE INTEGRITY: Package integrity should be verified afterthe sterilization process, before instruments are stored, and againimmediately before opening the package for use. Once the sterilizationcycle is complete and the physical monitors have been verified, surgicalinstruments should be allowed to cool and dry. If packages containmoisture externally or internally after sterilization and appropriatecooling, they should be considered contaminated. In addition tomoisture, packages should also be inspected for damage (e.g., tears,stains, or improper seals). If such packs are found, they should bereprocessed.PACKAGING MATERIALS: There are several choices in methods tomaintain sterility of surgical instruments, including rigid containers,peel-open pouches (e.g., self-sealed or heat-sealed plastic and paperpouches), roll stock or reels (i.e., paper-plastic combinations of tubingdesigned to allow the user to cut and seal the ends to form a pouch)and sterilization wraps (woven and nonwoven). The packaging materialmust allow penetration of the sterilant, provide protection againstcontact contamination during handling, provide an effective barrierto microbial penetration, and maintain the sterility of the processeditem after sterilization. In central processing, double wrapping can bedone sequentially or non-sequentially (i.e., simultaneous wrapping).Wrapping should be done in such a manner to avoid tenting and gapping.LOADING: Loading procedures must allow for free circulation of steam(or another sterilant) around each item. There are several importantbasic principles for loading a sterilizer: allow for proper sterilantcirculation; perforated trays should be placed so the tray is parallelto the shelf; nonperforated containers should be placed on their edge(e.g., basins); small items should be loosely placed in wire baskets; andpeel packs should be placed on edge in perforated or mesh bottomracks or baskets.STORAGE AND HANDLING: Safe storage times for sterile packs varywith the porosity of the wrapper and storage conditions (e.g., openversus closed cabinets). Heat-sealed, plastic peel-down pouches andwrapped packs sealed in 3-mil (3/1000 inch) polyethylene overwraphave been reported to be sterile for as long as 9 months aftersterilization. Supplies wrapped in double-thickness muslin comprisingfour layers, or equivalent, remain sterile for at least 30 days. Any itemthat has been sterilized should not be used after the expiration date hasbeen exceeded or if the sterilized package is wet, torn, or punctured.Aseptic technique is used to prevent contamination following thesterilization process. Sterile supplies should be stored far enough fromthe floor (8 to 10 inches), the ceiling (5 inches unless near a sprinklerhead [18 inches]), and the outside walls (2 inches) to allow for adequateair circulation, ease of cleaning, and compliance with local fire codes.Sterile supplies should not be stored under sinks or in other locationswhere they can become wet. Closed or covered cabinets are ideal butopen shelving may be used for storage. Any package that has fallenor been dropped on the floor must be inspected for damage to thepackaging and contents (if the items are breakable). If the package isheat-sealed in impervious plastic and the seal is still intact, the packageshould be considered not contaminated. If undamaged, items packagedin plastic need not be reprocessed.BIOLOGICAL INDICATOR TESTING: The biological indicator (BI) test, themost widely accepted method for monitoring steam sterilization, alsoknown as the spore test, provides a direct assessment of the sterilizer’slethality by killing highly resistant bacterial spores. Note that BIs onlytest one aspect of instrument reprocessing. Biological indicators arerecognized by most authorities as being closest to the ideal monitors ofthe sterilization process they measure the sterilization process directlyby using the most resistant microorganisms i.e., Bacillus spores, andnot by merely testing the physical and chemical conditions necessaryfor sterilization.CHEMICAL INDICATOR TESTING: Chemical indicators are convenient,are inexpensive, and indicate that the item has been exposed to thesterilization process. Chemical indicators are affixed on the outsideof each pack to show that the package has been processed through asterilization cycle, but these indicators do not prove sterilization hasbeen achieved. Preferably, a chemical indicator also should be placedon the inside of each pack to verify sterilant penetration. Chemicalindicators usually are either heat-or chemical-sensitive inks that changecolour when one or more sterilization parameters (e.g., steam-time,temperature, and/or saturated steam; ETO-time, temperature, relativehumidity and/or ETO concentration) are present. An air-removal test(Bowie-Dick Test) must be performed daily in an empty dynamic-airremovalsterilizer (e.g., pre-vacuum steam sterilizer) to ensure airremoval.CONCLUSIONSterility assurance practices require a comprehensive program thatensures operator competence and proper methods of cleaning andwrapping instruments, loading the sterilizer, operating the sterilizer,and monitoring of the entire process. Together, these methods willprovide sterility assurance and peace of mind regarding reprocessedinstruments.REFERENCES1. van Doornmalen J, Kopinga K. Review of surface steam sterilization for validation purposes.Am J Infec Control. 2008;36:86–92. Accessed 10th October, 2020.2. Dion M, Parker W. Steam sterilization principles. Available at: www.ispe.gr.jp/ISPE/07_public/pdf/201504_en.pdf.3. Seavey R. High-level disinfection, sterilization, and antisepsis: current issues inreprocessing medical and surgical instruments. Am J Infec Control. 2013;41:S111–S117.4. Centers for Disease Control and Prevention, National Center for Emerging and ZoonoticInfectious Diseases (NCEZID), Division of Healthcare Quality Promotion (DHQP) SterilizingPractices: Guideline for Disinfection and Sterilization in Healthcare Facilities (2008).Accessed 12th October, 2020.5. Kelli C. Mack, and Daniel A. Savett (2016). Assurance in Dental Instrument Reprocessing.Accessed 15th October, 2020.20 THE OPERATING THEATRE JOURNAL www.otjonline.com
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