Guideline for Sterilization

The updated AORN “Guideline for sterilization”1 was published in AORN eGuidelines+ in October 2024 and provides several new recommendations on sterilizing items for clinical use. “Sterilization gives us the greatest margin of safety and assurance that our instruments are safe to use,” said lead author, Amber Wood, MSN, RN, CNOR, CIC, FAPIC, senior perioperative practice specialist at AORN. “But to have that confidence, we have to follow the manufacturer's instructions.” The updated guideline acknowledges that there are instances when the device, sterilizer, and packaging manufacturers’ instructions for use (IFU) conflict.2 In such instances, it is advised to reach out to the product manufacturers to have them provide clarification—in writing if possible.1 “There is frustration when reconciling IFUs between devices, sterilizers, and packaging manufacturers because they often have conflicting parameters for sterilization and users are not sure which one to follow,” Wood said, noting that the guideline emphasizes the value of proactively reviewing IFUs when purchasing new devices to ensure that the sterilization methods are feasible for the facility. There is also a new recommendation that, when selecting a sterilization method for ophthalmic instruments, teams should select and use the sterilization method that carries the least risk of patient harm from exposure to chemical sterilant residues.1 Of note, certain low-temperature sterilization methods, such as ethylene oxide and hydrogen peroxide, might be contraindicated for these devices because there is a risk of toxic anterior segment syndrome.3 The Ophthalmic Instrument Cleaning and Sterilization Task Force recommends that low-temperature sterilization methods should be avoided unless both the device and the sterilizer manufacturer have ensured that the method is valid and does not pose an ocular toxicity risk.4 The updated guideline includes a new recommendation that states items produced through additive manufacturing (eg, 3D printing) should be sterilized in accordance with the manufacturer's IFU for the specific device, packaging, and sterilizer equipment.1 “There have not been really clear regulations for hospitals who are printing devices onsite, so we have provided guidance and some explanation of the necessary processes and regulatory requirements,” Wood said. She explained that processing a device made onsite can be complex as many of these devices can be made of materials, like polymers, that can melt or be deformed by the heat and pressure of sterilization or have intricate designs with voids or pathways that are difficult to sterilize.1, 5, 6 If the end user is to sterilize these products, even if they are for single use, the manufacturer is expected to provide cleaning and sterilization instructions.1, 6 Wood noted that, because many of these devices are experimental, staff members need to be aware of the regulatory requirements surrounding their use, which might include an institutional review board reviewing the device and its sterilization method. The guideline also recommends that facilities develop a process for determining the shelf life of sterilized patient-matched devices that were produced via additive manufacturing.1, 6 “These devices are customized to the patient and are made specifically based on a patient's anatomy,” Wood said. “However, the patient's anatomy could change over time, such as if the patient had a tumor that grew and changed, which is important to consider when establishing the product's shelf life.” The guideline recommends that the sterile processing area should be in a two-room configuration and have both a decontamination room and a clean workroom that are separated from each other.1 However, the guideline also contains a conditional recommendation intended to make it easier for outpatient facilities to comply, explained Wood. “When you have sterilization equipment limited to a tabletop sterilizer—which is what is commonly being used in an outpatient clinic—you can have a one-room sterile processing area instead of two separate rooms, so long as you have a clear separation between the clean and dirty areas,” she said. The updated guideline highlights new evidence supporting the recommended use of saturated steam under pressure to sterilize heat- and moisture-stable items.1 A 2022 study, which subjected dirty, uncleaned surgical instruments to sterilization by steam, ethylene oxide, or hydrogen peroxide gas plasma, demonstrated that steam sterilization was the most effective and had the largest margin of safety.9 Another study also found that steam sterilization had the largest margin of safety and the highest degree of efficacy in sterilizing test carriers that had been inoculated with test organisms.10 The updated guideline also highlights a large study that demonstrates that immediate use steam sterilization (IUSS) can be safely performed if the listed parameters outlined in the AORN guideline are followed.1 The use of IUSS is controversial, and AORN only recommends performing IUSS if certain conditions are met.1 However, this study found no significant difference in infection rates between patients whose procedures used items processed by IUSS and those whose procedures did not use IUSS-processed items.11 “The researchers were following the AORN guidelines and found IUSS to be safe to perform,” Wood shared. “Immediate use steam sterilization should not be a routine practice, but it is reassuring to know that, when you have to do it, it can be done safely.” In addition, AORN is among the first to use the verbiage “short cycle sterilization” in its guidelines. This is intended to alleviate some of the confusion surrounding short cycle sterilization and how it is different from IUSS. As the Centers for Medicare & Medicaid Services has clarified, short cycle sterilization and IUSS are not equivalent; short cycle sterilization refers to the sterilization of a wrapped or contained load that has a dry time and, unlike an item that has undergone IUSS, can be stored for later use.1 Moisture is not expected or accepted inside the package, again differentiating it from IUSS.1, 13 “Short-cycle sterilization is equivalent to terminal sterilization, and it is not considered IUSS if there is a dry time and it is packaged in a way that's intended to be stored for use,” Wood said. A table outlining the differences between terminal sterilization, short cycle sterilization, and IUSS is available in the guideline. A new recommendation states that liquid chemical sterilants are to be prepared in accordance with the water quality specification in the liquid chemical sterilant manufacturer's written instructions.14 This focus on water quality is in response to evidence demonstrating that poor water quality can reduce the efficacy of liquid chemical sterilization—the use of poor-quality water can interfere with dilution ratios, inhibit the removal of residual sterilant solution, and even contaminate the device during the final rinse.15 “Peracetic acid sterilization is a liquid chemical sterilization method, and it is important that, at the end of the liquid chemical sterilization cycle, you rinse it with sterile water or critical water,” Wood explained. “The guideline defines the parameters for what the qualities of water are; you don't want to contaminate the item after you've just processed it.” Similarly, the updated guideline advises that facility engineering personnel routinely monitor the water system that supplies steam generators (eg, the boilers).14 This is important because water supply system changes can negatively affect the steam quality and purity. Routine water supply monitoring allows for early identification of quality fluctuations or changes in construction or building operations.14 Finally, the guideline states that facility emergency operation plans should include an emergency water supply plan for sterile processing, as planning for a water shortage can help facilities continue in the event of a water supply disruption.1 “We want to make sure that leaders have an emergency plan if that were to occur and that they have a plan for managing the water supply,” Wood said. The updated AORN “Guideline for sterilization” provides new and updated guidance surrounding the selection of a sterilization method, designing a sterile processing area, transporting sterile items offsite, and sterilizing products manufactured via additive manufacturing.1 The guideline also provides further verification and clarification on IUSS and short-cycle sterilization and makes recommendations about water quality standards, monitoring, and planning. Items suitable for short-cycle sterilization should be in packaging that is suitable for storage. Emergency operation plans should include an emergency water supply plan for sterile processing, as planning for water shortages can help sterile processing personnel continue working in the event of a water supply disruption.