CDC 013-015: Sterilization

What reduces the heating and penetrating power of the steam?

Air that forms cool air pockets in the sterilizer.

What are the four essential parameters which depend upon the correct balance for ETO sterilization?

Concentration of the sterilant, relative humidity, temperature, and exposure.

What are the three phases of instrument processing?

Decontamination, sterilization, and sterile storage.

In what area are ultrasonic cleaners located?

Decontamination.

What must be done with a fresh solution before true ultrasonic cleaning can take place? How is this done?

Degassed; Operate the unit without instruments in the reservoir for a few minutes.

How is proper function of the sterilizing equipment ensured?

Done at least weekly with biological spore monitoring.

How should you remove instruments from the unit?

Never use your hands to remove instruments. Use the basket to lift the instruments from the solution, drain, and rinse under running water.

Chemical process indicators do not prove or guarantee what? What is their purpose? When must chemical process indicators be used?

That exact conditions and time required for sterilization are met. Therefore, they do not guarantee sterility of the pack contents. Provide a quick, easy way to visually identify whether or not the packs are processed. Both the exterior and interior of packages, unless the internal indicator is visible from the outside.

How can the speed and efficiency of the steam sterilizer be improved? What is this type of sterilizer?

(a) By removing air from the chamber with a powerful pump, creating a nearly perfect vacuum before steam is introduced into the chamber. (b) The prevacuum steam sterilizer.

What are the minimum documentation requirements?

(a) Date and time of test. (b) Sterilizer identification number. (c) Sterilizing conditions—temperature and exposure period (automated documentation, if available). (d) Person conducting test. (e) Results of control. (f) Results of test. (g) Nature and date of any malfunctions or repairs performed. (h) Load contents.

You should not store sterile items in what areas?

(a) In patient treatment or decontamination areas unless protected by enclosures such as drawers or cabinets. (b) With items not intended for clinical use (e.g., office supplies, cleaning supplies). (c) On the floor, under sinks, on window sills, adjacent to heating and air conditioning vents, or in any area where undetected contamination might occur.

What steps must be taken if any biological monitor reads positive?

(a) Positive result recorded in the dental sterilization log and the dental ICO notified. (b) Remove the sterilizer producing the positive test from service to prevent further use. (c) All instrument packs and items sterilized since the last negative spore test must be recalled and resterilized. (d) Medical equipment repair personnel must be contacted to check the sterilizer.

Why must the manufacturer's instructions of the sterilizer equipment be followed? Where should copies of operating procedures be located?

(a) The manufacturers make recommendations for appropriate cycle lengths and other operating parameters. Scheduled maintenance and calibration of sterilization equipment must be performed according to the manufacturer's recommendations. (b) Posted or readily available in all areas where sterilization is done.

What can you do to determine if a positive spore test is not the result of sterilizer malfunction?

Check the expiration dates on monitors, retest the sterilizer with the monitors, and check the incubator for proper function.

What is used as a means of quality assurance to monitor the sterilization process?

Chemical and mechancial process indicators, and biological spore monitors.

What precautions are taken when loading the sterilizer chamber?

Do not overload. The passage of steam from the top of the chamber to the bottom should not be blocked. Place all packages on edge, with large packs at the bottom of the chamber, and small packages in an upper layer crosswise to lower layer.

Why are items never placed directly on the bottom of tanks?

Doing so reduces the amount of ultrasonic waves produced and can damage the unit.

What type of sterilizer uses forced air at higher temperatures to rapidly transfer heat and achieve sterilization? What are the time and temperature requirements for sterilization?

Dry heat convection unit. 12 minutes at 375°F (190°C) for wrapped items and 6 minutes for unwrapped items.

Why does the saturated steam process take longer for large linen packs?

Each successive layer must be penetrated by saturated steam and heated as the steam condenses on the cool material. This process continues until all areas of the pack have been heated to the same temperature as the surrounding steam.

Why is ultrasonic cleaning of contaminated instruments safer than manual cleaning?

Eliminates the possibility of accidental puncture wounds on hands which frequently occurs with manual scrubbing. Eliminates the splatter of organism-laden debris generated by scrubbing with a brush.

When is ETO considered an acceptable method for USAF dental clinics?

For nonheat stable dental instruments when available through the MTF CSS.

What types of spores are used to test steam under pressure and sterilization? Which are used in dry heat and ethylene oxide?

Geobacillus stearothermopilus; Geobacillus atrophaeus.

What are three types of widely-used steam sterilizers?

Gravity displacement sterilizer, prevacuum high-temperature sterilizer, and instrument washer sterilizer.

ETO is recognized as an acceptable method of sterilization for what type of items and by whom?

Heat and moisture-sensitive items; the ADA and CDC.

Identify the two types of nylon tubing; and the suitable sterilization method.

Heat-stabilized used in dry heat only; nonheat stabilized for steam only.

When must sterilized items be resterilized?

If the wrapper becomes wet, if the pack touches the floor, if there is any question of contamination, or if the safe storage period has expired.

Where are the results of all sterilizer testing recorded?

In a dental sterilization log.

Explain how instruments are decontaminated in washer-sterilizers

Instruments used in patient care are placed in rigid, reusable container systems, such as cassettes or baskets. The cassettes or baskets are loaded into the washer-sterilizer which cleans the objects with mechanically agitated water and detergent, similar to that of a dishwasher.

What happens to the pH indicator in the medium after incubation?

It changes color when spores germinate and produce acids, which then visually identifies a failure in the sterilization process.

What are the disadvantages of the high temperatures of dry heat sterilization?

It destroys many rubber- and plastic-based materials, melts the solder of most impressions trays, and weakens some fabrics, as well as discolors other fabrics and paper materials.

What may happen if items made of carbon steel are steam-sterilized?

It dulls their cutting edges.

Briefly explain time-related shelf life.

It is identified with an exact expiration date. After this date, the item is considered to be outdated and should not be used.

What is the purpose of using pressure? Briefly explain.

It is used only to raise the temperature of the steam and, in itself, has nothing to do with microbial killing action. At 15 psi, the boiling point increases to 121°C (250°F), a temperature at which all known organisms are killed.

What are the requirements if a container is used to transport instruments to central sterile or substerile areas?

It must be red in color or be affixed with a biohazard label.

What is a common misuse of the dry heat method?

It occurs when the oven is opened and an instrument is quickly removed during the timed cycle. This interrupts the cycle, and timing must begin all over again.

What must take place after the sterilization is complete to maintain sterility?

Items must dry completely before removing.

What should you frequently spot-check sterilizers for?

Leaks in lines and improperly functioning gauges, dials, thermometers, doors, drain strainers, and valves.

How is the sterilizer loaded if mixed loads of metal items and linen are sterilized together?

Linen is placed on the upper shelf and metal items on the lower.

What must be done if the Bowie-Dick test indicates inadequate air removal?

Medical equipment repair personnel must be notified and the sterilizer must be repaired before the prevacuum cycle can be used.

Who should check the sterilizer, if it does not appear to function properly?

Medical equipment repair personnel.

Why must packs or containers be arranged loosely in the sterilizer chamber?

Overloading the chamber prevents achieving sterilization evenly throughout the load.

Briefly explain how to carry out the sterilization test using autoclave tape.

Place 3 or 4 pieces of tape on the fabric in a crisscross manner with the fabric layer arranged in a test pack that allows the tape strips to extend from the edge to the center of the pack at a given layer depth. Conduct the test after the warm-up cycle is completed. Place the test pack in the bottom front of an otherwise empty chamber. After exposure open the test pack and check the tape. The tape shows by its color change the pattern of residual air, if any, that remained in the pack during the sterilization cycle. Uniformity of the color change, not the intensity, is the significant factor.

What is final sterilization? When is it accomplished?

Processing items after terminal sterilization. After assembling, and wrapping of packs or trays.

What two areas should be physically separated from the remaining sterilization areas?

Receiving and decontamination.

What designated work areas should the sterilization area include?

Receiving, decontaminating, preparation and packaging, sterilizing, storing, and issuing.

Why is the use of washer-sterilizers beneficial?

Since the instruments are processed through the washer-sterilizer prior to technician handling, the risk of injury from contaminated instruments during processing is greatly reduced.

What sterilization methods are suitable for perforated cassettes?

Steam and dry heat methods (some cassette systems are not compatible with dry heat).

What sterilization method is suitable for paper or combination paper/plastic materials?

Steam sterilization.

What are the crucial components of the steam-under-pressure process?

Steam temperature and exposure time.

What methods of heat sterilization are currently accepted in USAF dental clinics?

Steam under pressure (autoclave) either gravity displacement or prevacuum, dry heat, and unsaturated chemical vapor.

What method of sterilization is compatible with cloth wraps? How often must reusable cloth wraps be laundered and inspected for tears and pinholes?

Steam; after each use.

What is event-related shelf life?

Sterility is maintained indefinitely if packages are handled and stored properly.

What information is placed on the label of packs, trays, or cassettes? When and how is this done?

Sterilizer identification number, preparer's initials, and date of expiration. The label and date must be entered using a pencil, ink marker, preprinted indicator tape, or a marking device that won't run or fade when exposed to sterilization before the items are placed in the sterilizer.

What factors are considered when assigning shelf life?

Storage location (open or closed shelves), conditions of storage areas (cleanliness, humidity, temperature), type of packaging or wrapping material.

Why are supplies never put into a heated sterilizer until it is time for the sterilization to start?

Supplies exposed to such heat before sterilization causes fabrics to dry, superheat, and incur damage during sterilization.

Since infection control standards call for sterilization of all instruments that will or are likely to penetrate the soft tissue, what does this include?

Surgical instruments, rubber dam clamps, scalers, scalpels, periodontal probes, and matrix retainers.

What are the temperature and time requirements for dry heat sterilization?

Temperature of 320°F (160°C) for 2 hours or 340°F (170°C) for an hour.

Identify and define the type of sterilization achieved after the washer-sterilizer cycle is complete.

Terminal sterilization. Sterilizing items immediately after use in patient care before further processing.

What must be done if instruments cannot be immediately decontaminated?

They must be placed in a rigid, leakproof container containing a disinfectant solution or enzyme cleaner until ready for processing.

What must be produced before returning a repaired sterilizer to use?

Three negative spore tests.

Why must the lid or cover always be on the unit when it is in operation?

To decrease aerosols and avoid splattering of the solution onto adjacent surfaces.

What is the basis of steam under pressure sterilization?

Transfer of heat to an article by condensation.

Briefly describe how steam sterilizers should be cleaned. Why?

Use a mild detergent to wash the surfaces. Follow the wash with a thorough rinse of plain water. Unless this is done, the chamber walls will collect mineral deposits and may become greasy.

What are the requirements for accomplishing the destruction of microorganisms by dry heat in a dental facility?

Using a unit that has been tested and approved as a commercial sterilizer by the FDA.

What are the benefits of a central sterilization area?

Usually safer and more cost-effective than performing instrument processing in the DTR.

What alternative methods result in a no touch system which reduces the potential for injury during instrument processing?

Washer-sterilizers and washer-decontaminators.

How must all packs or rigid containers be labeled?

With the sterilizer identification number, initials of the person who wrapped the pack, load number, and the date of expiration.

What takes place in the processing area?

All inspecting, sorting, wrapping, and packaging of materials.

What will cause the pressure required to maintain sterilizing temperature to vary?

Altitude.

How are instruments prepared for sterilization after decontamination?

Arranged as packs or trays with the necessary materials and supplies. Placed into a wrap or container suitable for the sterilization method used. Sealed and labeled to include the sterility expiration date.

As a recommended standard, when is steam sterilization achieved?

At 250°F or 121°C after 20-30 minutes at 15 psi.

How often must the solution be changed?

At least daily or sooner if visibly contaminated.

When is biological spore monitoring required?

At least weekly on all sterilizers in use, and for every load with an implantable device.

How much ultrasonic solution is required in the reservoir?

At least ½ to ¾ full and must completely cover the items for the ultrasonic action to occur.

What is the most reliable way of determining the effectiveness of the sterilization cycle and sterility of processed items?

Biological spore monitors.

Why is the packaging of supplies and loading of the sterilizer important?

Both must be done so that the steam comes into contact with all areas of surfaces of the items being sterilized.

What test was developed for prevacuum sterilizers to determine if the air has been removed from the chamber during the prevacuum stage?

Bowie-Dick.

What makes ultrasonic cleaning of instruments more effective?

Bursting bubbles scrub everywhere the liquid can penetrate. Intricate surfaces and difficult access areas are cleaned more thoroughly and rapidly. Use life of cutting instruments is extended by thoroughly removing debris that interferes with cutting surfaces. Some disinfecting ability through the mechanical disruption of bacteria.

At what temperature and length of time are wrapped instruments sterilized in a prevacuum sterilizer?

270°F (131°C) after 4-minute exposure.

What is the time limit for ultrasonic cleaning?

5 minutes unless longer times are specified by the manufacturer.

When storing sterilized items how do you arrange them?

According to expiration date, placing items with later dates toward the rear.

How is the air removed from the chamber in the gravity displacement sterilizer? What slows this process when the sterilizer is filled with supplies?

Air is evacuated downward and outward from the chamber through the chamber discharge line. Air may be trapped around and, more frequently, inside the supplies, keeping the steam from contacting all portions of the items and preventing sterilization in that area.

To whom and how are the results of spore testing reported?

The MTF infection control committee in the format and on a schedule dictated by local policy.

What is one of the most common problems with the use of dry heat sterilization?

The failure to properly time the exposure.

What must the selected method of sterilization be compatible with?

The items to be sterilized, sterilization wraps, adhesives and containers.

Specify where biological spore strips or ampules should be placed within the sterilizer.

The location least accessible to the sterilizing agent which is usually within an instrument pack located in the lower front of the sterilization chamber in steam under pressure sterilizers or in the center of the load for tabletop units.

Why must instruments be thoroughly decontaminated before they are sterilized?

The presence of blood, tissue, oil, or other materials present a barrier to steam or heat, and may render chemical agents completely ineffective.

Why are fluids sterilized separately?

The pressure must be slowly released.

Define sterilization. Specify what this includes.

The process by which all forms of life are completely destroyed. The destruction of all microbial life forms such as bacteria, fungi, viruses, and bacterial spores.

What causes the cycle of the prevacuum sterilizer to vary?

The size of the sterilizer, the adequacy of steam, and the supply of water.

What other area should you check when a positive spore test occurs? Why?

The sterilization log. Review it for evidence of recent repairs, maintenance, or past malfunction of the sterilizer.

Define flash sterilization.

The sterilization of unwrapped items in a gravity displacement or prevacuum sterilizer with recommended minimum exposure times and temperatures.