Sterilization

EO Sterilants

100% EO: Single-dose cartridges of EO have become the most commonly used EO sterilant in healthcare facilities. Cartridges of 100% EO should be stored and used in a well ventilated area (at least 10 air exchanges per hour). OSHA does not permit more than one day's supply (not to exceed 12 cartridges) in the department unless stored in a flammable cabinet. Personnel should wear neoprene, butyl rubber gloves, and goggles or a face shield when handling either full or spent EO cartridges and when transferring sterilized items to the aerator. EO Mixtures: are usually supplied in large cylinders or tanks. The cylinders or tanks must be secured with a chain or other device to prevent them from tipping over. Storage areas must be well vented (10 air exchanges per hour) and conform to the sterilant manufacturers recommended temperatures.

Monitoring The Sterilization Process

A chemical indicator specific to EO sterilization must be placed inside each package. A lot label must be placed on each package to be sterilized. Each load should be biologically monitored because of the critical parameters of the EO sterilization process. Biological indicators containing Bacillus Atrophaeus should be used. A test pack is usually placed in the geometric center of the load; placement depends on the size and type of EO sterilizer. Labeled and documented.

The EnvironmentTemperature & Humidity

AAMI recommends that the temperature in the sterilization area be 68℉ to 73℉, and the relative humidity be 35% to 60%, with an ideal humidity level of 50%. The temperature and humidity should be documented daily. The recommended ventilation is 10 air exchanges per hour under positive pressure. The area behind the steam sterilizers and sometimes, the EO sterilizers. AAMI recommended temp for the sterilizer access area is 75℉ to 85℉. Ventilation is 10 air exchanges per hour under negative pressure.

Unloading The Sterilizer

All EO sterilized items must be aerated after sterilization because EO is toxic and all residues must be removed before the items are handled or used. If the sterilizer does not have an integral aeration cycle or if the load must be transferred to a mechanical aerator because the sterilizer is needed to process another load, the sterilized items should be transferred to the aerator as soon as possible after the sterilization cycle is complete. If a cart is used to transfer the load, the cart should be pulled, not pushed, to reduce the risk of exposure to airborne EO. Sterilizers with integral aeration cycles typically provide three hours of aeration at the end of the sterilization phase of the cycle. (sterilizer cannot be opened, safety feature). At the end of the aeration period, sterilized items can be transferred to a stand-alone aerator for additional aeration. Items sterilized that do not need to be transferred can remain in the sterilizer for the remainder of aeration.

Documentation

All items processed should be recorded using a paper, electronic, or digital record-keeping system. The contents of each load should be recorded: the lot number, the number of items, a description of the items, and the using departments. Lot control numbers enable each sterilized device to be tracked. The lot control information, which should include the sterilizer number, the cycle or load number, and the date of sterilization, is usually affixed to each item with a lot control label gun.

Monitoring The Sterilization Process

An important responsibility of the CS/SPD technician is to ensure that all parameters for sterilization are met. Administrative Monitoring Physical Monitoring Chemical Monitoring Biological Monitoring

Preparation Of Items For EO Sterilization

As with all methods, items must be thoroughly cleaned before sterilization. Items to be EO sterilized must be completely dry. (Ethylene glycol (antifreeze) can be produced when EO reacts with water) Most packaging materials that are acceptable for steam sterilization are also acceptable for EO sterilization. Packages must allow for adequate penetration of EO and its subsequent release. Trays for containing items should be perforated and should be placed flat in the sterilizer. Rigid sterilization containers should be tested in the sterilizer in accordance with AAMI standards. Paper-plastic peel pouches should be placed on edge; in a large-chamber sterilizer, they should be contained in a basket.

Incubation Of Bi's

Biological indicators should be placed in an incubator at the temperature recommended by the BI manufacturer. Typical temperatures are 55℃ to 60℃. The incubation temperature is important because the bacterial spores used in BIs for steam sterilization only grow at specific elevated temperatures.

Summary

CS/SPD technicians need to be competent in all practices pertaining to disinfection and sterilization"

Sterilization Process Failures

Can occur for several reasons: The presence of non-condensable gases when the steam is treated with chemicals. Inadequate steam pressure. Inadequate time at temperature. Incorrect usage and placement of BI PCDs and Bowie-Dick test packs.

Monitoring

Chemical: Provided by the sterilizer manufacturer is red when unprocessed; the red changes to yellow after exposed to hydrogen peroxide. This changes occurs in both the external & internal indicators. Biological: For this process contains the spore Geobacillus stearothermophilus. A test should be performed daily. A BI is incubated at 58C (136F) for 24 hours.

Employee Monitoring

Compliance with the PEL is determined on the basis of one or more air samples representing full-shift exposure for each shift for each job classification in each work area. The air must be sampled from the "breathing zone" (between the nose and upper chest) of personnel. It is recommended that routine employee monitoring is performed to ensure that EO exposure levels do not exceed OSHA standards. All EO monitoring results must be shared with each employee within 15 days of receipt of the results. (in writing, or posted) If the PEL has been exceeded, the notification must include a written plan of action. Monitoring data, as well as medical surveillance data, must be recorded and maintained for 30years after termination of employment.

Phases Of The Cycles

Conditioning Phase: during this phase, air is removed from the sterilizer chamber and steam is injected. Sterilization/Exposure/"Holding" Phase: in this phase, the prescribed exposure temperature is maintained for a prescribed amount of time. Exhaust Phase: after the exposure phase, steam is exhausted from the sterilizer through the chamber drain line. Drying Phase: after the steam has been exhausted, the sterilizer goes into the drying phase of the cycle, which typically last about 30 minutes. To achieve drying in a dynamic-air-removal steam cycle, filtered air is drawn into the chamber. In a gravity-displacement cycle, the heat in the chamber walls causes moisture to evaporate.

BI Test Results

Depending on the BI used, the color of the sterilized BI should be unchanged or show no fluorescence, signifying that the spores were killed. (a neg. result) The control will turn yellow (a positive result)

Drying

Drying is critical to sterility maintenance. If packages are still moist when the sterilizer door is opened, bacteria can land on the package and "wick" or travel inside the package. In a dynamic-air-removal steam sterilizer, the drying takes place in HEPA-filtered air. In a gravity-displacement sterilizer, drying takes place by evaporation resulting from heat in the chamber walls and is thus much less efficient.

Two Basic Steam Cycles

Dynamic-air-removal Pre-vacuum sterilizers remove air by drawing a series of vacuums with an injection of steam between each pull. Gravity-displacement Air removal is achieved with the sterilizing chamber pressure at above-atmospheric pressure. (no vacuum is required to remove air for sterilization) Many healthcare facilities today use pre-vacuum steam sterilizers that can be programmed to run a gravity-displacement cycle when needed. In gravity-displacement cycles, incoming steam displaces residual air through the drain at the bottom of the sterilizer chamber.

Ethylene Oxide Sterilization (EO)

Ethylene oxide (EO) is a chemical agent used in healthcare facilities for the sterilization of heat-pressure- or moisture-sensitive items. Ethylene oxide is a liquid that becomes a gas at room temperature. In both liquid and gaseous state, 100% EO is highly flammable and explosive. It is colorless and essentially odorless.

Potential Risks Associated With Ethylene Oxide

Ethylene oxide is a toxic substance, but it's benefits outweigh its risks. The toxic effects of EO result from exposure by inhalation, ingestion, or direct contact with tissue. Sterilizer operators must be able to demonstrate a complete understanding of the properties and hazards of EO and the sterilization process. EO residuals, if not completely removed by adequate aeration, can cause irreversible tissue damage-even death. Act responsibe Wear PPE.

Regulations Related To EO Use

Ethylene oxide is regulated by OSHA, EPA, and FDA. The primary regulations affecting CS/SPD personnel are those by OSHA for employee safety and hazard communication. OSHA regulations specify requirements for employee monitoring, sterilizer installation, engineering controls, medical surveillance, and emergency situations, as well as other measures designed to protect employees from excessive exposure to EO.

Flash Sterilizers

Flash sterilizer are most often located in the OR and in ambulatory surgery centers. They can also be found in some labor and delivery departments. Flash sterilization is appropriate in emergency situations, as when a one-of-a-kind item is dropped on the floor during surgery or otherwise becomes contaminated and is needed urgently.

Unloading Sterilizer Cart

Hands must be clean. Items should be placed on a lined cart with a non-linting material and transferred to the storage area carefully. Packages with holes or tears must be brought back for reprocessing.

Infrared Thermometers

Healthcare facilities have recently begun using infrared thermometers to determine the temperature of packs. If such a device is used, it is not necessary to touch packs to determine whether they are cool. The suggested release temperature is 70degrees to 72degrees F.

Temperature And Pressure

In a steam sterilization cycle, temperature and pressure are interrelated. For each temperature, there is a necessary pressure to reach that temperature. The higher the temp, the higher the pressure needed, the lower the temp, the lower the pressure needed. The temperature also has a direct bearing on the sterilization time; in general, the higher the temperature, the shorter the time. The minimum exposure times, temperatures, and pressures used should always be those recommended by the steam sterilizer manufacturer.

Phases Of Sterilization

Injection, Diffusion, Plasma: The injection, diffusion, and plasma phases are repeated a second time. Vent: At the end of the second sequence, the RF energy is turned off. Air is vented into the chamber through bacterial HEPA filters, returning the chamber to atmospheric pressure. **At the end of the cycle , a 10 second continuous audible alarm sounds, alerting the operator. The printer prints out a summary of the cycle parameters.**

Biological Monitoring

It is recommended that biological monitoring of sterilization cycles be performed routinely (weekly, preferably daily), for every load containing implants, after a positive BI test, and for qualification testing. Qualification testing is performed when a new sterilizer is installed, when a sterilizer is relocated, and when a sterilizer has a major repair. Process Challenge Device (PCD)- device that presents a challenge to the sterilizer to ensure that sterilization parameters were met; formally known as a biological-indicator test pack.

Chemical Monitoring

Process indicators (Class 1) are also referred to as external CIs. An example of a Class 1 CI is indicator tape. Indicators for specific tests (Class 2) are used in certain test procedures, such as the Bowie-Dick test. Single-variable indicators (Class 3) are designed to respond to only one variable of the sterilization process that they are designed to monitor. Multi-variable indicators (Class 4) are designed to react to two or more of the variables of the sterilization process that they are designed to monitor. Integrating indicators (Class 5) are designed to react to all critical variables of the specific sterilization process that they are designed to monitor Emulating indicators (Class 6) are designed to react to all critical variables of the specific sterilization process that they are designed to monitor. At present, AAMI, AORN, and the CDC do not provide specific recommendations for the use of Class 6 indicators

Product Quality Assurance Testing

Quality assurance testing of routinely processed items representing a product family should be tested periodically, and when "major changes, weight changes, or changes in the type of packaging material. If any test indicates a problem, the cause of the problem should be investigated, the problem should be corrected, and the products should be retested.

Gravity-Displacement Cycles

Some medical devices cannot withstand the temperature or vacuum of a pre-vacuum sterilization cycle. It is important to note that the drying of packs in a gravity-displacement cycle is more difficult to achieve. This cycle should be restricted to only those devices that require gravity-displacement.

Steam Sterilization Cycles

Steam sterilization cycles have three parameter: Saturated steam under pressure Time Temperature The time and temperature vary with the steam sterilization method.

Principles Of Sterilization

Sterility is the absence of ALL forms of microbial life, including bacterial spores. Steam sterilization and other sterilization processes are generally designed to kill one million bacterial spores. As the sterilization process progresses, the bacterial population decreases. Steam sterilization is accomplished by saturated steam under pressure. Steam under pressure sterilizes devices quickly and efficiently. Steam kills microorganisms by denaturing (coagulating) the protein. Steam is the most common form of sterilization used in healthcare facilities for items that are heat-and moisture- tolerant.

Steam Sterilizers

Sterilizers Using Boiler-generated Steam: The sterilizer needs a dedicated supply of steam. The steam is generated inside a boiler. The pressure required is usually 60 to 80 psig (pounds per square inch gauge). The steam pressure can be checked by means of a gauge located on the main steam line for the department. The internal chamber is surrounded by an insulating jacket. The jacket provides heat inside the chamber to prevent condensation from forming on the chamber walls. The heat-sensing thermometer is located in the drain line, which is the coldest part of the sterilizer.

Bowie-dick Test

The Bowie-Dick test is used to detect air leaks, inadequate air removal, inadequate steam penetration, and the presence of non-condensable gases (i.e., air or gases from the boiler additives). The Bowie-Dick test is performed daily for dynamic-air-removal cycles of pre-vacuum sterilizers. If the sterilizer's steam is shut off at night, the Bowie-Dick test should be performed for the first cycle of the day. If the sterilizer is run throughout the day and night, the test should be performed at the same time each day for consistency. If the sterilizer's steam is shut off at night, the Bowie-Dick test should be performed for the first cycle of the day. If the sterilizer is run throughout the day and night, the test should be performed at the same time each day for consistency. Bowie-Dick test packs can be constructed in the department or purchased pre-made. It should always be verified that a commercial test pack meets AAMI standards (ANSI/AAMI ST 79)

The Joint Commission (Flash)

The Joint Commission will now focus its survey efforts on the entire sterilization process, not just on the amount of flash sterilization performed......they will review three critical steps of reprocessing: Cleaning and decontamination Sterilization Storage or return to the sterile field

EO Sterilization Cycles

The basic parameters of EO sterilization are gas concentration, exposure time, humidity, temperature, and, in the case of sterilizers that use EO mixtures, pressure. The humidity level is critical to EO penetration of bacterial cells and thus to successful sterilization. Ethylene oxide kills microorganisms by a process known as alkylation; the removal of hydrogen from the chemical structure of the microorganism. Alkylation interferes with the normal metabolism of the microorganism, causing it to die. For EO to penetrate cell walls, microorganisms must be hydrated.

Unloading The Sterilizer

The load can be take out of the sterilizer immediately. Items must remain on the sterilizer cart, untouched until they are COMPLETELY cooled. Cart should remain in a low-traffic area. Cart should not be placed under air intake or exhaust ducks

Loading The Sterilizer

The load configuration needs to ensure adequate air removal, steam penetration, and steam evaluation and drying. Instruments with mesh bottoms and rigid containers should be placed flat on the sterilizer rack. Instruments with solid-bottom trays (even those with small holes), should be tilted on their edge (side). Textile packs should be placed on their side to facilitate air removal (through the folds) and steam penetration. Peel Pouches should be placed on their edge (side) with the clear side of one pouch, facing the paper side of the next pouch. Rigid sterilization containers should be placed flat with sufficient space between each container to permit air removal and steam penetration. Wrapped items (including peel pouches and instruments in mesh-bottom trays) should never be stacked.

Loading The Sterilizer

The load should be arranged so that metal items are in a single layer and do not touch the walls, doors, or electrode of the sterilizer. The most effective sterilizer performance is achieved when the load contains a mixture of metal and plastic items. The chamber must not be overloaded. All Tyvek pouches should be placed on their edge.

Method Of Sterilization

The method of sterilization that is appropriate for a particular medical device is dictated by the device manufacturer (IFU), NOT by CS/SPD. Sterilizers are usually located in the preparation and packaging area adjacent to the sterile storage area.

LTGP Sterilization Cycles

The parameters for LTGP sterilization are: Time Temperature Sterilant: Multi-dose cassette containing 10 single doses of liquid hydrogen peroxide.

Employee Monitoring

There are three types of limits on exposure to EO: Permissible exposure limit (PEL); the amount of airborne EO to which personnel can be exposed may not exceed 1 ppm (Parts per Million) as an eight-hour time-weighted average (TWA). Action level: which is currently set at 0.5 ppm as an 8 hour TWA. This is the level that additional monitoring and/or other actions must be taken. Excursion limit (EL): which is set at 5ppm as a 15 minute TWA: to determine whether the EL is being met, EO levels are measured over a period of 15 mins. while personnel are performing specific activities.

Engineering Controls

There must be a dedicated exhaust for EO systems and EO sterilization areas. The ventilation needed is positive pressure with 10 air exchanges per hour. Sterilizers and aerators must be vented to the outside of the building. The vent must not end within 25 feet of any opening into the building.

Aeration

Two Types Of Aeration: Ambient aeration: which takes place at room temperature without the benefit of air exchanges. There must be a designated room with dedicated air exhaust and a minimum air rate of 10 air exchanges per hour. Usually takes at least seven days. This type of aeration is more commonly done by medical device manufacturers than by healthcare facilities. Mechanical aeration: is usually performed either within the sterilizer chamber or in a stand-alone aeration cabinet. It must have a dedicated exhaust and provide continuous, filtered air washes. Typical aeration times and temperatures are 122F for 12 hours, 130F for 10 hours, or 140F for 8hours. It is critical that the CS/SPD tech verify the temperature and times of each cycle. And sign.

Biological Monitoring

Two Types of PCD's are available for sterilizers larger than 2 cubic feet: PCD with a conventional BI PCD with an enzyme-based early readout BI For flash sterilization cycles two types of BIs are available: Conventional BI Enzyme-based early-readout BI

Preparation Of Items For LTGP Sterilization

Preparing items for LTGP sterilization is similar to preparing items for steam or EO sterilization. All devices processed must be thoroughly cleaned and dried; any residual moisture can cause cycle cancellation. (compressed air can be used to blow out moisture) Must be packaged in non-cellulous-based materials.

Emergency Plan

Under OSHA regulations, facilities that use EO must have a written plan for "emergency situations". Defined by OSHA as "an occurrence such as Equipment failure Rupture of containers Failure of control equipment that may result in an unexpected, significant release of ETO". The department must have a visible and audible alarm to alert employees of a potential emergency situation. A written emergency plan must be available in the department.

EO Cycle Phases

Vacuum- All air is removed from the chamber and packages. Humidification- A small amount of moisture is automatically added to the chamber. Introduction of sterilant- EO enters the chamber. Exposure:- The load is held at the specified temperature, gas concentration, and (if applicable) pressure for the specified time. Final vacuum- The chamber is repeatedly purged (in some units) to remove sterilant. Aeration- Some types of sterilizers have integral aerators to remove sterilants, and others, the sterilized items must be removed from the chamber and transported to a separate aerator. OSHA and some states require that sterilizer operators demonstrate competence in EO sterilizers cycle parameters as well as a comprehensive knowledge of the system in use

Phases Of Sterilization

Vacuum: All air is removed from the chamber and the packages until the pressure is reduced to below atmospheric pressure. Injection: A premeasured amount of concentrated (59%) hydrogen peroxide(H2O2) is pumped from the cassette into the valve vaporized bowl and vaporized into the chamber. Diffusion: The chamber returns to atmospheric pressure and hydrogen peroxide vapor is driven into the small crevices and lumens of the devices in the chamber. Plasma: The chamber pressure is reduced by vacuum, and radiofrequency (RF) energy is radiated within the chamber from the electrode screen. The RF energy ionizes the hydrogen peroxide creating H2O2 gas plasma and leading to the generation of free radicals and other chemical species that destroy organisms.

Wet Packs

Wet packs represent one of the greatest problems in sterility maintenance. AORN and AAMI recommend against the use of an item that is wet or a set that contains visible moisture. (Even if it is in a rigid container) Whenever wet packs occur, a complete investigation of the cause must be conducted and corrective actions implemented.

Control Bi's

Whenever a test BI is used, a control BI (one that is not sterilized) is needed. Must have same lot number as testing BI's A new control is incubated each day Must be identified with a date and a "C" for control. The control BI is used to verify that the spores were viable before they were sterilized. The control must show a positive result in order for the test results to be valid.

Low-temperature Gas Plasma Sterilization

LTGP was cleared by FDA in 1993 as an alternative to EO gas. A quick, low temperature sterilization process that uses gas plasma for packaged devices. Sterilant without the hazards or extended aeration times associated with EO. The LTGP sterilizer requires only a special electrical outlet so it can be located almost anywhere.

Routine Load Release

Non Implants: A BI PCD may be used to release non implant loads but is not required. Implants: All loads containing implantable devices (e.g., screws, plates) should be biologically monitored. Implants should be quarantined until the results of the BI are known.

Peracetic Acid

Peracetic acid is FDA-cleared as a liquid chemical sterilant 2 cycles: liquid chemical sterilization cycle; to process devices Diagnostic cycle: to test system.