May 19, 2021

ANSI/AAMI ST79 amendments refine sterilization practices

By: Susan Klacik, BS, CRCST, ACE, CIS, FCS

Amendments have been added to the Association for the Advancement of Medical Instrumentation (AAMI) standard ANSI/AAMI ST79, Comprehensive Guide to Steam Sterilization and Sterility Assurance in Health Care Facilities. The standard, which is used in healthcare facilities to guide their sterilization processes, is considered a useful resource to promote best practices.

Four new amendments recommend ways to enhance environmental cleaning and ventilation, as well as instrument inspection and testing. They also stress the importance of following sterilizer manufacturers’ instructions for use (IFU) and clarify the documentation needed for biological monitoring.


Amendment 1: Environmental Services/Fans/Food and Drink

Section Design considerations was added to specifically state that food and drink should not be permitted in any area where medical devices are processed because they can contaminate prepared and sterilized items and attract insects.

Environmental cleaning verification using adenosine triphosphate as recommended in AAMI ST79 Amendment 1: Environmental Services/Fans/Food and Drink.
Photo courtesy of Susan Klacik.

This new section also recommends that the sterile processing department (SPD) or other areas that perform SP functions follow the same housekeeping procedures as those used to clean ORs. Floors and horizontal work surfaces should be cleaned at least daily. Other surfaces in an SPD, such as walls, storage shelves, and air intake and return ducts, should be cleaned on a regular basis and more often, if needed. High-level environmental cleaning of areas such as ceiling vents, tops of equipment, and workstation lights, and low-level environmental cleaning of surfaces such as base boards, sterilizer base, and cart bottoms, should be performed routinely as well. Lighting fixtures or covers should be cleaned at least once every 6 months, and stained ceiling tiles should be replaced.

A cleaning schedule should be followed, and a cleaning checklist can help track whether appropriate cleaning is being performed. A sample of an environmental checklist, which includes the monthly cleaning and disinfection of sprinkler heads, has also been added to this section. The manufacturer’s IFU should be reviewed before cleaning sprinkler heads.

Cleaning verification tools such as ultraviolet visible markers and adenosine triphosphate (ATP) bioluminescence are available and should be used to measure the adequacy of environmental cleaning on work surfaces. Information regarding the cleaning effectiveness should be provided as feedback to personnel performing the cleaning task; providing this measurement can improve the cleaning quality.

New recommendations have been added to Section Heating, ventilation, and air conditioning (HVAC) operating parameters for ventilation systems, including those pertaining to the use of fans and the effects of doors and windows. Only ventilation system fans and properly installed and operating fume control fans can be used. Fixed and portable fans should not be used in SP areas. The ventilation system should be designed so that air flows from clean areas—which are under positive pressure—to soiled areas under negative pressure.

The environment has an impact on the safety of the devices processed, so it is important to keep bioburden and environmental contaminants at bay. The use of down-draft-type air circulation systems limits contamination by carrying contaminants toward the floor and away from work surfaces. Fans are not permitted in any SP area because they create highly turbulent airflow, which recirculates dust and microorganisms from the floor and work surfaces—thus interfering with designed airflow characteristics. Windows and doors that affect the ventilation and airflow should be kept closed to further limit the risk for environmental contamination.


Amendment 2: Inspection of Insulated Instruments

Two new sections have been added to Section 8: Preparation and assembly of instruments.

Section 8.2, which addresses the inspection process, emphasizes the fact that damaged instruments or incomplete instrument sets/trays may cause a delay or cancellation of a surgical procedure, and/or increase risk of patient harm related to instrument malfunction. Several steps can be taken to prevent such incidents.

• Each time a medical device is processed, it should be visually inspected for cleanliness and integrity. Enhanced inspection with magnification, borescopes, or other inspection methods to verify cleanliness and integrity may be used.

• A method should be in place to ensure the cleanliness and integrity of every instrument and medical device. Upon inspection, medical devices with retained soil or residue should be subjected to repeated cleaning and decontamination processes until the devices are completely clean.

• Damaged instruments should be removed from service (damaged instruments should be addressed according to the healthcare organization’s policies and procedures). Methods used to change instruments from their original state—such as using an engraver that can cause fractures or surface damage—should not be performed. Review the equipment IFU to ensure the correct type of inspection equipment is available and whenever new devices are being purchased.

Insulation integrity testing of an electrosurgical instrument as recommended in ST79 Amendment 2: Inspection of Insulated Instruments.
Photo courtesy of Susan Klacik.

Section 8.2.1 addresses the inspection of instruments intended to be used with electric current (otherwise known as electrosurgical instrumentation). Electrosurgical instruments are insulated and typically used in minimally invasive surgery. They are susceptible to physical and mechanical damage as well as degradation related to repeated use. Using insulated instrumentation with holes in the insulation or other defects places patients at risk for significant harm. If holes are not detected during instrument processing and the damaged instruments are used during a procedure, the insulation breach can result in an electrical current escape that can burn the patient.

Insulated instruments should be carefully inspected—including their cords, which can become damaged during normal use, processing, contact with sharp instruments, and use of high-voltage electricity. Organize instruments (such as in instrument sets) to protect them from damage.

To prevent patient harm, insulation testing for insulation integrity is recommended each time the instruments are processed, in accordance with the instrument manufacturer’s written IFU for inspection. There are different types of insulation testing methods, and they vary with insulation tester type. There are also a variety of accessories to test specific instrumentation and cables/cords, based on their design. For that reason, it is vital to refer to the instrument and insulation tester manufacturers’ written IFU for their recommended procedures.

Insulation testers are designed to detect small current leaks that can jeopardize patient safety. Any time instrument insulation does not pass inspection, the device should be immediately removed from service, and damage should be addressed according to the healthcare organization’s policies and procedures that address instrument evaluation, repair, or replacement.

A table was added that addresses the inspection points and possible damage for various instruments/devices. This table lists the name of the instrument/device, followed by its inspection points (as well as the possible damage to the medical device), and methods to assist with inspection/testing. This quick-reference inspection guide will be helpful as these instruments are processed.

Images of instrument and cord failures are provided to help illustrate what to look for in electrosurgical instrumentation and cord failure.

Before processing instruments, staff should be educated about the proper use of all testing equipment. Competency should be verified and documented before they use the equipment.


Amendment 3: Modification of Content Pertaining to Frequency of Cleaning for Routine Care of Sterilizers for Sterile Processing Areas in Health Care Facilities

Under Section 12.4: Routine care of the sterilizers, new wording was added to strengthen the recommendation for following the sterilizer’s IFU, which may require that weekly or other prescribed inspection and cleaning be performed (and it should be documented, per internal procedures).


Amendment 4: Content Addressing Recording Biological Indicator Lot Numbers in Sterilizer Records for Sterile Processing in Health Care Facilities

This amendment revises the wording in Sections BI PCD test procedure, Test procedure, and Test procedure to better clarify the specific documentation when performing biological monitoring.

The amended standard is available at ANSI/AAMI ST79:2017 Comprehensive Guide to Steam Sterilization and Sterility Assurance in Health Care Facilities will be automatically updated for users with an AAMI eSubscription. Those who previously purchased the printed version or have a PDF version will receive a PDF of the amendments via email at no cost. ✥

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