This series of self-study lessons on Central Service topics was developed by the International Association of Healthcare Central Service Materiel Management (IAHCSMM). The lessons are administered by Purdue University’s Continuing Education Division.
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Healthcare facilities have used traditional steam sterilization time, temperature and dry cycle standards for more than three decades to process utensils, power equipment, single instruments, and instrument sets, among other items. However, medical instrumentation manufacturers are now incorporating routine and complex designs and materials into their devices that increasingly lengthen these traditional recommendations. This lesson provides an overview of extended cycle challenges that confront Central Sterile Supply Department (CSSD) personnel..
AAMI has offered standard steam sterilization cycle recommendations to produce efficiently-processed medical instrumentation with minimal errors for more than 30 years. Examples of these recommended standard cycle times for gravity-displacement and dynamic-air removal steam sterilizers are shown in Figure 1. Note: The information contained in these figures incorporate normal variations in sterilizer manufacturers’ recommendations at different temperatures. It is always important to consult and utilize written recommendations provided by the manufacturers of the sterilizers used at specific healthcare facilities.
Objective 2. Explain common reasons why manufacturers may recommend extended steam sterilization cycle times for medical devices
While the AAMI-recommended standard cycle times shown in Figure 1 are used today, many medical devices now require extended sterilization times, and CSSD professionals must rethink and revise traditional steam sterilization parameters.
Extended cycle times result from the written recommendations of medical device manufacturers. They can range from up to one hour in a gravity-displacement steam sterilizer and up to a 30-minute exposure in a dynamic-air-removal sterilizer (compared to the much shorter cycle times for these sterilizers shown in Figure 1)
Figure 1: Examples of Standard Cycle Times.
CSSD personnel must obtain, study and consistently follow the manufacturer’s written recommendations for the medical devices they process. They must implement a policy that these written recommendations be provided by the manufacturers for all items purchased, consigned or loaned to the facility to help ensure that items requiring extended sterilization times are identified and properly processed. These recommendations should be filed and used for reference and training purposes. They should also be available for easy access by CSSD technicians, and a copy should be retained in the supervisor’s office. Note: When new medical devices are introduced in the facility, the CSSD manager should receive a copy of the instructions for review when the items are evaluated.
Extended exposure times are most frequently encountered in orthopedic and neurological instrument sets because:
The above factors create a more significant challenge to air-removal and steam penetration during steam sterilization cycles. Other common examples of instruments requiring extended sterilization cycles include loaner instrumentation sets with a dense metal mass that require additional steam contact. Also, power equipment and instruments with lumens or crevices may need to be processed in rigid containers, instrument cases, cassettes, organizing trays, or other containment devices comprised of materials including plastic and/or metal that increase sterilization challenges.
Extended exposure times can also be related to the country of origin. European medical device manufacturers may recommend an extended (18-minute) pre-vacuum cycle of 274°F (134°C) to inactivate prions which cause Creutzfeldt-Jakob Disease (CJD). These recommendations do not change when devices are imported to the United States.
Objective 3: Discuss common challenges that confront CSSD professionals as they monitor instruments in extended cycles
CSSD professionals use chemical indicators (CIs) and biological indicators (BIs) and corresponding challenge packs that are designed, tested, and qualified for use as process monitors in steam sterilizers operating at the traditional exposure times and temperatures indicated in Figure 1. A BI qualified for use in a gravity displacement sterilizer operating at 248°F (120°C) for 30 minutes should not be used in a pre-vacuum steam sterilizer cycle at 273°F (134°C) for 4 minutes unless the BI manufacturer has validated its use and provides label claims for the second cycle.
CSSD personnel use a limited number of steam cycles for routine sterilization. Their sterilizers are validated by the manufacturer to yield the appropriate steam sterilization conditions for the specific cycles noted in Figure 1, and users do not typically alter them after installation of the sterilizer. Significant problems occur when cycle times recommended for new medical devices extend beyond the traditional times. In fact, extended times for affected devices may be 5-20 minutes or even longer at 270-275°F (132-135°C) in dynamic air-removal sterilizers.
Sterilizer use time and daily processing capacities are impacted by extended steam sterilization cycles when medical devices with specific extended cycles require a dedicated sterilizer cycle. For example, processing backlogs can be created that impact other sterilization loads.
Most manufacturers require standard cycle times (Example: 4 minutes at 270-275°F [132-135°C] in a dynamic-air-removal sterilizer) based on device material and design. Damage to some items can occur if these items are processed with other devices requiring an extended cycle in the same load. Also, the manufacturers’ specific instructions must be followed, so facilities may be legally liable if items are damaged or compromised and then fail during a surgical procedure. Another potential problem: device replacement costs will also be the facility’s responsibility.
Examples of extended steam sterilization cycle times are shown in Figure 2.
Figure 2: Examples of Extended Steam Sterilization Times2
Objective 4: Provide an overview of how manufacturers and users verify sterilization instructions
Extended sterilization cycles have created concerns about the validation responsibilities of medical device and sterilizer manufacturers, and user verification is important.
Medical device manufacturers must validate cleaning and sterilization processes for their instruments. To do so, BIs are placed in the most challenging areas of the medical devices which have prompted the need for extended sterilization cycles. Examples of these locations include the corners and centers of containment devices, next to a large metal mass, by lumens, and among instruments on stringers. Manufacturers of containment devices should indicate the most challenging locations where indicators should be placed.
Sterilizer manufacturers use tests specified in the ANSI/AAMI ST8: 2001 Hospital Sterilizer Manufacturer Standard to validate that their equipment operates the way it is intended to perform.3 Test data for specific cycle parameters must be submitted to the U.S. Food and Drug Administration (FDA) for clearance.
CSSD sterilizer users must verify that cleaning and sterilization processes are effective and that the methods used by their facility are consistently performed according to the medical device manufacturers’ instructions and ANSI/AAMI ST79: 2010 recommended practices.1
This verification is done by product testing.4
Objective 5: Explain the need to follow manufacturer’s instructions when processing instruments for immediate use (flash sterilization)
In 2010, a position paper relating to immediate use sterilization was developed and released by stakeholders representing AAMI and other healthcare associations including IAHCSMM.5 It addresses flash sterilization problems and provides guidance about sterilizing medical devices for immediate use.
The guidelines require that medical devices sterilized in surgery for immediate use must be processed with the sterilization times and temperatures specified in the medical device manufacturer’s written instructions. It also notes that (a) cycle parameters to achieve sterilization are determined by instrument design, load characteristics, sterilizer capabilities, and packaging, if used, and (b) the device manufacturer’s instructions may not be compatible with instructions provided by the sterilizer or the container/wrapper manufacturers.
Instructions provided by the device manufacturer may be unclear, incomplete, or require unavailable processes or cycles. When instructions conflict or are insufficient, the device manufacturer should be contacted and, when differing instructions cannot be resolved and the instrument is urgently needed, the device manufacturer’s instructions must be followed. This includes the use of extended sterilization cycles, if recommended.
1. Association for the Advancement of Medical Instrumentation. Comprehensive guide to steam sterilization and sterility assurance in health care facilities. ANSI/AAMI ST79. 2010.
2. Examples shown are from:
(A) - Alfa, M. et al. User Alert: Problems with Process Monitors for Extended Steam Sterilization Cycles. 2006.
(B) - DePuy Reprocessing Instructions for Use of Reusable Non-Sterile Instruments. Rev. A1FU- 0902-05-001.
3. Association for the Advancement of Medical Instrumentation. Hospital Steam Sterilizers. ANSI/AAMI ST8. 2001.
4. Readers desiring more information about product testing are referred to: Extended Cycles. Training Achievement Program. Chicago, IL. International Association of Healthcare Central Service and Materiel Management. In production.
5. Association for the Advancement of Medical Instrumentation. Immediate-Use Steam Sterilization. Position Paper. 1/31/1. Note: other healthcare associations including IAHCSMM are represented in this position paper.
Scott Davis, CMRP, CRCST, CHMMC
Susan Klacik, ACE, CHL, CRCST, FCS
Patti Koncur, CRCST, CHMMC, ACE
Natalie Lind, CRCST, CHL
David Narance, RN, CRCST
Carol Petro, CRCST, RN, BSN
Patti Koncur, CRCST, CHMMC, ACE
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