CRCST
Technical Continuing Education (TCE)
SELF-STUDY PLANS

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.

EARN CONTACT HOURS:
You can use these lessons as an in-service with your staff, or visit www.iahcsmm.org for online grading at a nominal fee ($5 per single lesson plan, or bundled packages are available for quantities of 6 lessons for $25 (save $5) or 12 lessons for $50 (save $10) for greater savings).

Each lesson plan graded online with a passing score of 70% or higher is worth one point (contact hour). You can use these points toward your re-certification of CRCST (12 points).

Mailed submissions to IAHCSMM will not be graded and will not be granted a point value.

To order a paper/pencil subscription for the CRCST Lesson Plans, please call Purdue University at 877-537-7732. IAHCSMM does not provide written grading service for any of the Lesson Plan varieties, and Purdue University ONLY provides written grading services for the CRCST Lesson Plans (not the ICE or SCE Lesson Plans).

Lesson Plan CRCST 101
Basics of Steam Sterilization
[Reprinted from Communiqué: July/August 2008]

Sterilization is the complete destruction of all microbial life using physical or chemical procedures. In this lesson, you will learn why steam sterilization is the method of choice, details about basic types of healthcare steam sterilization equipment, and procedures to monitor sterilization cycles, properly maintain sterilizers, and abort loads.

Objective 1: Explain the advantage of steam sterilization.
Steam sterilization is the preferred method to destroy microorganisms in Central Service operations. The process is non-toxic, safe, sporicidal (it kills spores), and relatively inexpensive. Several packaging options, both rigid and wrapped, have well-documented efficacy records. Using these options with multiple suppliers helps keep steam sterilization costs low. Other sterilization methods are used only when the item being sterilized cannot withstand the heat or moisture of steam sterilization. One potential disadvantage of steam sterilization is that the steam may not be pure and, therefore, its quality must be monitored. Also, precautions must be taken when items are packaged and loaded into the sterilizer to ensure that steam will contact all items to be sterilized.

Objective 2: Discuss the basic types of steam sterilizers.
There are four basic types of steam sterilizers: Gravity Air Displacement, Dynamic Air Removal, Flash Sterilizer, and Washer-Sterilizer.

Gravity Air Displacement Sterilizers use gravity to remove air from their chambers. Steam introduced into the chamber creates a layer above the air, which increases until the air is pushed down through a drain at the bottom of the unit. After the air is removed, steam temperature and pressure builds, and exposure time begins when the sterilization temperature is reached. Gravity sterilizers are used to sterilize surgical instrumentation, liquids, and linen.

Dynamic Air Removal Sterilizers (also called prevacuum, “prevac,” and pulse vac steam sterilizers) overcome one problem that might occur when using saturated steam in gravity cycles: air can be trapped in the chamber, causing cool air pockets to form, which hinders sterilization. Prevacuum sterilizers use a pump to remove air from the chamber before steam is introduced. Dynamic air removal units are, therefore, more efficient than gravity air displacement sterilizers because air is pumped out before steam enters the chamber, so the steam can immediately penetrate packages. A Bowie-Dick air removal test, or an equivalent test, should be used daily with these sterilizers to determine if there is residual air in the chamber. Air pockets can prevent steam from reaching all surfaces of the items, resulting in sterilization failure.

Flash Sterilizers are typically located near operating room suites, and they are used to quickly sterilize dropped instruments using cycles with minimum exposure times and temperatures for unwrapped items. Sterilized items must be transferred immediately from the sterilizer to the operating room using an aseptic technique to minimize recontamination from pathogenic (disease-causing) organisms. There is still a risk that flash-sterilized items can be contaminated, however, during transport to the point of use. Exposure times for flash sterilizers depend on load contents and applicable recommendations from the equipment manufacturer. Documentation of the flash sterilization process should be consistent with documentation requirements for sterilizing wrapped items.

Washer-Sterilizers are usually located in areas next to, or very close to operating room suites. These combination units wash and sterilize instruments; however, gross contamination should be removed and rinsed from instruments before they are processed. These units use a mechanical cycle to wash and rinse away debris before the sterilization cycle begins. While this processing method yields instruments that are safe for handling, it is not appropriate for immediate patient use. The instruments must be inspected to assure that they have been adequately cleaned before flash or routine packaging and sterilization.

Objective 3: Review the basics of the steam sterilization process.
Steam alone is not adequate to achieve sterilization. To kill microorganisms, pressure greater than the atmosphere is also required to increase the temperature of the steam. Microbes die when steam under pressure creates changes in cell structure, and when cell protein coagulates (thickens into a mass).

The first steps in sterilization involve proper cleaning (the removal of visible and invisible soil) and decontamination (the removal or reduction of infectious organisms or other harmful substances). Failure to adequately prepare an item for sterilization hinders the direct steam contact needed to destroy microorganisms.

Steam sterilization requires four critical parameters: steam, temperature, pressure, and time. Steam must be of high quality and contain no more than 3 percent moisture and a relative humidity (the amount of water vapor) of 97 percent. The appropriate temperature depends upon the type of sterilizer being used. Gravity air displacement sterilizers require a temperature of 250°F (121°C). Dynamic air removal, washer sterilizers, and flash sterilizers require a temperature of 270°-275° F (132°C-135°C). To achieve these temperatures, the pressure must reach 15 pounds per square inch (psi) for the 250°F (121°C) setting, and 27 psi to sterilize at 270°F. Note: Because the psi required to reach sterilization temperatures is related directly to the altitude, the exact psi required may vary slightly by geographical location. It is always best to consult the sterilizer’s manufacturer for requirements in your area.

Required exposure time depends upon the sterilizer manufacturer’s recommendations based upon load contents. Gravity air displacement sterilizers could have a thirty minute exposure time with a thirty minute drying time, while dynamic air removal units may use a four minute sterilization exposure time and a twenty to thirty minute drying time cycle. Washer sterilizer and flash sterilization times vary from three minutes to ten minutes, depending on load contents. An additional eight minute drying time may be added for power equipment during a flash cycle. Note: These times represent the D-values for the different sterilization processes. A D-value is the amount of time required to kill 90 percent of the microorganisms present, and it varies according to factors including the sterilization process used, temperatures, type of microorganisms present, and soil conditions.

Packaging should ensure that contents remain sterile until opened for use, and it should also provide aseptic delivery of contents to the sterile field. All instruments should be opened and disassembled to allow the steam to completely contact all surfaces of the items during sterilization. Items wrapped in polypropylene should include a towel to help absorb moisture and to reinforce the bottom of the pan which, in turn, will help prevent packaging rips and tears. Packages should also contain a steam chemical indicator on each level of the pan. Sterilizer operators must know what wrapping and labeling is acceptable, and they should perform the last inspection of all items before sterilization.

Proper loading of the sterilizer cart is critical to sterilization because items must be arranged to allow for direct steam contact and drying. The sterilizer operator should be able to place a hand between wrapped items; approximately one inch of space is required. Peel pouches should be placed on edge, plastic-to-paper (not plastic-to-plastic) to ensure that steam will easily penetrate through all pouches. Do not overload the sterilizer’s shelves or compress packages. In loads that combine fabrics and hard goods, place the instrument trays on the lowest shelf. Packages wrapped too tightly or over-crowded packs can cause air to become trapped, allowing cool air pockets to form in the chamber. Provide at least three inches between the sterilizer’s chamber ceiling and the top package of the load. Do not allow wrapped instrument sets to contact the sterilizer’s chamber walls. Rigid containers act as heat sinks during the sterilization cycle and can create condensation that may drip on wrapped sets, causing wet packs, and so should be placed below wrapped sets.

When the sterilization cycle is completed, the door should be opened six inches to help assure proper evaporation. Before removing, the contents should dry twenty-five to thirty minutes for a gravity air displacement unit and ten minutes for a dynamic air removal sterilizer. Note: Contents of washer-sterilizers and flash sterilizer units should be removed when the sterilizer cycle is completed. To avoid heat injuries, always use an insulated oven mitt when unloading the sterilizer. Place the sterilizer cart in a location where there is no air conditioning or nearby cold air vents. Visually inspect the outside wrappers for dryness. If water droplets or visible moisture are noticed on package exteriors, these are considered non-sterile wet packs and they must be repackaged and re-sterilized. In addition, look for packages in which the tape has loosened, because this can compromise package integrity. Staff should visually inspect chemical indicators (for example, sterilization wrapping tape and dots on peel pouches and tamper-evident seal devices).

Items should be allowed to cool on the sterilizer cart for one to three hours. Document the time the load came out of the sterilizer on the sterilizer load list. Do not handle warm packages or place them on cold, solid surfaces, which can cause condensation and compromise package integrity and sterility. Moisture and bacteria from one’s hands can move through packaging material until it is cool. Do not handle, dispense, or store packages until they have cooled completely.

Proper handling and storage is required to maintain package sterility. Storage room temperatures should be 64°F-75°F (18°C-24°C) with humidity of less than 75 percent. Staff should limit handling to maintain the packages’ integrity, and bottom shelves of storage units should be solid to prevent floor dust and dirt from rising through the shelving to settle on sterile packages.

Objective 4: Explain procedures for routine monitoring of sterilization cycles. Sterilization cycles should be monitored routinely using mechanical, chemical, and biological indicators. Every sterilized item requires a control label with tracking information, including date, sterilizer number, and sterilization load number. An item is not considered sterile if the control label is missing. Labels should be inspected before sterilization, before storing, and before dispensing any item.

At the beginning of the sterilization cycle, packages should be arranged properly and a control label sticker should be placed on each item. All packages should be listed on the sterilizer load list, counted while on the sterilizer cart, and compared to the number of items on the load list. Both totals must match. In the event of a recall, every item entering the sterilizer must be accounted for.

The top portion of the chemical indicator control card is then completed and placed in the middle of the sterilizer cart, on the middle shelf. This card shows exposure to the sterilant by changing color. Load contents should then be placed in the sterilizer using either a carriage or floor-loading system. The correct cycle parameters are then selected, the door is closed, and the cycle is started.

On the sterilizer load list, document the time the door was opened at the end of the sterilization cycle. At the end of every cycle, the sterilizer printout should be initialed by the sterilizer operator and checked for the following information:

• start time and date,
• operator’s initials, and
• sterilizer parameters used.

The operator should also confirm that the time allowed for the load contents was adequate and that the temperature did not fall below the required temperature. Also, the operator should verify that the pressure was 15 psi (for gravity air displacement units) or 27 psi (for dynamic air removal sterilizers), and that the cycle load number matches the load number on the control label sticker.

Effective documentation ensures that the sterilization process is monitored as it occurs, that required cycle parameters have been met, and that accountability has been established. Sterilization records are considered legal documents and, because the length of time they must be kept varies, each healthcare facility must develop record-retention policies based upon state and local regulations and legal considerations.

If an error occurs during the documentation process, it should not be erased or “whited out.” A line should be drawn though the error, the correction should be recorded, and the operator and supervisor should initial the correction. Always use a black pen (not a felt marker) for documentation. Create a sterilization control folder each day for each sterilizer, and label each folder with the date, sterilizer number, and department information. Each load should be documented and placed in the folder. At the end of the day, each folder should include the control cards, load content lists, and printout tapes for that sterilizer for each load.

Biological indicator (BI) test packs monitor the adequacy of the sterilization process and the destruction of microorganisms. They contain an inoculated carrier (Geobacillus stearothermophilus for steam sterilization) that provides a defined resistance to the sterilization process in which they will be used. Sterilizer operators should verify that the date on the BI pack has not expired, and the test pack should be placed on the bottom shelf, in front of the sterilizer cart, above the drain. A BI should be included in each sterilizer at the beginning of each day, and in all loads that contain implantables.

A load control label should be attached to the BI. When the sterilization cycle ends, the BI should be processed following the manufacturer’s written procedures. At least one non-sterilized BI should be activated each day, and it is expected to be positive for growth. The control lot number must be the same as the sterilized biological lot number. If the lot number of the biological test pack changes, a new control must be activated for the new lot number. Read and record the results following proper procedures.

A sterilizer shift report is required, and any errors that are identified must be corrected before the end of the operator’s shift. The operator and relief operator should verify:

• any sterilizer problems,
• number of loads running,
• BIs, if any, currently in a sterilizer, and BIs
• that must be read,
• any biological controls that must be read,
• that lot numbers on controls match the BIs being used,
• that the first daily BI has been processed and read,
• that the printout tape matches the control folder information,
• that all control cards are included in appropriate control folders,
• that Bowie-Dick, or similar air removal tests have been processed and read, and
• the number of loads being cooled whose contents must be properly stored.

Objective 5: Describe procedures for sterilizer maintenance and for aborting loads.
Sterilizer maintenance is important. Sediment screens should be removed and cleaned daily because clogged strainers prevent air from being removed from the unit. Sterilizer operators should inspect door gaskets for defects or signs of wear or deterioration, and they should be cleaned or replaced as needed. Chamber interiors should be cleaned weekly with a mild detergent. Note: Sterilizers must be allowed to cool for eight hours before cleaning. Carriages, carts, and loading baskets should be washed with a mild detergent each week. Casters, rollers, and other moving parts should be cleaned and checked to ensure that they move freely. Maintenance requirements differ depending on the model used, and the sterilizer manufacturer’s instructions should always be followed.

Sterilizer monitoring systems recognize cycles only when they are completed, and the printout will indicate if a cycle is aborted. All items in an aborted load must be repackaged and re-sterilized. Operators may manually cancel a load if the wrong cycle was selected or if an item is urgently needed by the physician. A request to cancel a load to obtain instruments for immediate use, however, should always be discussed and approved by a Central Service manager.

Resources for Additional Information

1. Association of Operating Room Nurses (AORN). Recommended Practices for Sterilization in the Perioperative Practice Setting. Standards, Recommended Practices, and Guidelines. 2007.
2. Comprehensive Guide to Steam Sterilization and Sterility Assurance in Health Care Facilities. ANSI/AAMI ST79. 2006.
3. High Temperature Sterilization. Chapter 15 in International Association of Healthcare Central Service and Materiel Management. Central Service Technical Manual. Seventh Edition. 2007.