Devices must be completely submerged in the LCS/HLD solution (activated, diluted, or ready-to-use) for the specified time and temperature, and the sterilant/disinfectant must be at the correct concentration. The solution should be visually inspected before each use and discarded if precipitates are noted, even if the solution is within its usable life.7 The concentration of the active ingredient in solutions should be monitored before each use. Because biologic and chemical indicators are generally not available or labeled for use with liquid chemical sterilants/high-level disinfectants, most manufacturers provide solution test strips or chemical monitoring devices for use with their products (FIGURE 4). The test strips monitor for the concentration of active ingredients. A thermometer and timer are used for physical monitoring and documentation of manual LCS/HLD processes for each cycle. Disposable water temperature verification strips are also available to help assess cycle efficacy.7 Upon completion of the LCS/HLD process, the sterilized/disinfected items are manually rinsed using aseptic technique as described in the CDC or Association for the Advancement of Medical Instrumentation (AAMI) standards, or according to the manufacturer’s IFU. If the device is not rinsed in sterile water, its sterility will be compromised.  FIGURE 4. Agent-specific test strips are used to determine if a solution has maintained effective concentration levels with prior use and storage. Healthcare personnel must be advised of the hazards associated with the chemicals they work with, and they should be provided with education and safety procedures to ensure compliance, as per OSHA Hazard Communication Standard (29 CFR 1910.1200). In general, healthcare personnel should avoid direct contact with liquid chemical sterilants/high-level disinfectants. Personnel should wear appropriate personal protective equipment (PPE) to prevent skin and eye contact with the solutions (FIGURE 5). Furthermore, these solutions should be used in a well-ventilated area and kept covered to prevent inhalation exposure to the fumes. Recommended aeration or rinsing procedures must be followed after use of these chemical sterilants, as per the manufacturer’s IFU. Finally, each facility should designate and train a liquid chemical sterilant/high-level disinfectant spill containment response team to ensure that spills can be cleaned up safely.7 FIGURE 5. It is imperative to wear appropriate personal protective equipment, as advised by the manufacturers’ instructions for use, when handling liquid chemical sterilants. Sterilization IndicatorsSix classes of chemical indicators (CIs) are used to assess parameters identified as being essential or critical to the sterilization process. The variables considered critical for effective sterilization may include different parameters based on the sterilization process being used. For example, steam sterilization parameters include time, temperature, and water (as delivered by saturated steam), but those considered critical for effective EO sterilization involve time, temperature, relative humidity, and EO concentration.1,2 Some CIs use a reactive ink technology that produces a chemical reaction driven by exposure to process variables and results in a color change. “Moving front” CIs possess tablets that melt in response to steam and temperature and wick down a paper path. Class 1 (process indicators): These are used externally as an exposure control (e.g., indicator tapes) on individual units to distinguish between processed and unprocessed units. Class 1 indicators are relatively simple and are designed to react to one or more of the critical process variables. Class 1 indicator tapes are agent specific, meaning that, for example, a class 1 steam indicator tape would not work as a class 1 indicator tape for an EO unit. Class 2 (test sterilizer performance during a specific test procedure, such as a Bowie–Dick test): Bowie–Dick testing can detect anomalies such as air leaks, inadequate air removal, inadequate steam penetration, or the presence of noncondensable gases (air or gases from boiler additives) in vacuum-assisted sterilizers. Class 3 (single-variable indicators): These are designed to react to one of the critical variables and indicate exposure to a sterilization process at a stated value (SV) of the chosen variable. Class 3 indicators may become obsolete. Class 4 (multi-variable indicators; usually paper strips): These are designed to react to 2 or more critical variables. This type of CI indicates exposure to a sterilization cycle at an SV of the chosen variables. Class 5 (integrating indicators): These are designed to react to all critical variables. The SVs for a class 5 indicator are equivalent to the performance requirements for biologic indicators (BIs).11 Their response must correlate to a BI at 3 time/temperature relationships: 250°F/121°C, 275°F/135°C, and one or more temperatures in between, such as 263°F/128°C. SVs must be listed on the product or provided on the label/IFU (FIGURE 6). Again, class 4 and 5 indicators for steam sterilization are different than class 4 and 5 indicators for EO. FIGURE 6. Class 5 (integrating) indicators are designed to react to all critical variables and are identified as the CI type providing the highest level of sterility assurance. To determine the efficacy of a steam sterilization cycle using a 3M Comply SteriGage (as shown), the black bar must wick into the ACCEPT zone. Class 6 (emulating indicators): These are cycle verification indicators that are designed to react to all critical variables for specified sterilization cycles. The SVs are generated from the critical variables of the specified sterilization process. Class 6 indicators are cycle specific and must pass an appropriate dry heat test; their response does not correlate to a BI. BIs contain >100,000 viable spores of a highly resistant organism on a strip and therefore are considered the most reliable level of testing available. Using BIs during a sterilization cycle provides the only direct method of demonstrating lethality within that particular load.1,2,12 BIs may also be used during low-temperature sterilization methods such as EO, hydrogen peroxide gas plasma, and ozone sterilization processes. Nonetheless, it is possible to have a negative BI and still have a CI failure elsewhere in the load.2 Healthcare facilities can either process BIs on site using test vials and an incubator or contract with a sterilization monitoring service (FIGURE 7). FIGURE 7. As an alternative to running and incubating biologic indicator tests on site, sterilization monitoring service is available through outside companies such as SPS Medical. (Quarterly SPS Medical report pictured with class 5 indicators.) A process challenge device (PCD) is an item (pack/tray) designed to create a defined resistance to a sterilization process and is used to assess the performance of the sterilization process. For example, a Bowie–Dick test ensures the sterilizer is removing air efficiently in dynamic-air-removal (i.e., vacuum-assisted) steam sterilizers and detects trapped air within the sterilizer, which can compromise sterility. A PCD containing a BI is considered a BI challenge test pack/tray, whereas a PCD containing only a class 5 integrating indicator is considered a CI challenge test pack/tray. In large facilities, PCDs are often run at the beginning of each day.1,2,12 ConclusionVeterinary technicians play a key role in ensuring that medical devices are clean and functional before HLD and sterilization, and much can be learned from the mistakes made in human medicine. Regularly updating hospital policies and procedures and verifying the efficacy of cleaning and sterilization processes can play a vital role in preventing HAIs during the pursuit of excellence in veterinary patient care. AcknowledgmentsThe author would like to thank Renee Lombardi, veterinary assistant, and Jennifer Mathieu, LVT, at Oakland Veterinary Referral Services, for their assistance with this article. Portions reprinted with permission from Reuss-Lamky H. Beating the “bugs”: sterilization is instrumental. Veterinary Technician 2011;32(11):E1-E9. aSusan Flynn, BESc, CSPDT, technical service specialist, 3M Health Care, Sterilization Assurance Group, St. Paul, MN, oral communication, April 2008. References
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Which method would a nurse use for a high-level disinfection
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