Chapter 11 - Sterilization Flashcards by Treasa Clifford

What is the Spaulding classification regarding instruments for sterilization?

Critical - come into contact with the bloodstream or sterile tissue (instruments, needles, catheters should be sterile)
Semi-critical - Come into contact with mucous membranes or non-intact skin (ETT, laryngoscopes, high-level disinfection)
Non-critical - Contact only intact skin (stethoscope, BP cuff, intermediate level disinfectants)

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What is toxic anterior segment syndrome (TASS)?

Uveitis from not washing all the cleansers off ophtho instruments.

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What are the main options for cleaning of surgical instruments prior to sterilization?

Manual cleaning with enzymatic cleaners or detergents (no bubbles)
Mechanical cleaning of surgical instruments (preferred method)
Ultasonic cleaning with cavitation, washer decontaminators, washer disinfectors and washer sterilisers. Instruments must be thoroughly rinsed after cycle is complete

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What is the only approved method for drying instruments prior to sterilization?

Filtered, medical grade compressed air

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What are the (9) ideal properties of a wrapping material?

Prevent microbial penetration
Permeable to the sterilising agent
Resistant to heat
Allow for aeration
Resistant to physical damage and moisture penetration
Possess minimal wrap memory
Long shelf-life with sufficient strength and durability
Free of toxic ingredients and dyes
Provide a barrier to microorganisms and fluid

Does not exist!

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What is the most common wrap material? What are its downsides?

Cotton muslin wrap
- Can generate lint
- Not moisture resistant
- Requires a double layer

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List the methods available for sterilization:

Liquid chemical germicides (cold sterilization)
Steam sterilization
Ethylene oxide sterilization
Ozone sterilization
Plasma sterilization
Vaporized Hydrogen Peroxide
Sterilization by radiation

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List some options for cold sterilization. What are the problems with cold sterilization?

Glutaraldehyde 1-1.5%
Orthophthalaldehyde (Cidex)
Hydrogen peroxide 7.5%

Should be considered high level disinfectants rather than sterilization. Glutaraldehyde is irritating to skin and can decrease pulmonary function.

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How do steam sterilizers work?

Kill microorganisms through coagulation and denaturation of proteins by moist heat
- Water serves as a catalyst and allows lower temperatures to be used

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What are the 2 types of steam sterilizers?

Gravity-displacement (steam rises to the top and cool air is removed though a valve at the bottom)
Prevacuum type - A pump is used to remove air before steam is admitted to allow for very rapid and uniform steam distribution

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What are the temperature and time options for gravity-displacement autoclaves?

121C for 30 minutes with 15-30mins drying
132C for 15 minutes with 15-30mins drying

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What are the potential causes of wet packs after steam sterilisation?

Improper loading
too large metal mass
Overloaded tray
Lack of absorbent materials
Insufficient cooling time

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What is the recommended temp and time for dry heat sterilisation? When is this indicated?

160C for 120 mins
Certain sharp instruments, glassware and powders that can be damaged by moisture

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What are the guidelines for flash sterilisation of a metallic, unwrapped, nonporous item in a gravity-displacement autoclave?

135C for 3min with 1 min drying
“immediate use steam sterilization” is for emergencies, burns can result from temperature. Not for implantable devices.

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What are the safety concerns surrounding ethylene oxide?

Carcinogenic, mutagenic and neurologic hazards

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What is ozone sterilization used for? What is the recommended temp and time?

Good option for moisture and heat-sensitive items.
-NO wood/paper
30-35C for 4 hours

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What is plasma sterilization?

Use of electromagnetic energy to create a plasma phase from a vapor of hydrogen peroxide, oxygen or peracetic acid/H2O2mix
Rapid and cost effective
45-59C for 28-75min
NO linens, liquids, wood

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What is used for radiation sterilization?

Cobalt 60 gamma rays or electron accelerators
Suture and implants
Expensive

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What are the 6 classes of sterilization indicators?

Class 1 - Indicates the pack has been processed but limited info regarding parameters met - eg external tape
Class 2 - Test for air removal (“Bowie-Dick test”)
Class 3 - React to a specific parameter
Class 4 - React to more than 1 parameter
Class 5 - React to all parameters which are important for a certain type of sterilization
Class 6 - Monitor more specific guidelines for unique parameters (eg combatting prion infection)

Recommended to always use a class 1 indicator as well as an additional indicator in the deepest part of the pack

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What biological indicator is used for steam sterilisation (as well as plasma and ozone)

Geobacillus Stearothermophilus
One study found 12% failure rate on biological indicators, none of which were detected by simultaneous chemical indicators

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What are the ideal conditions for storage of sterilized materials?

Temp should not exceed 24C
Humidity should not exceed 70%
4 air exchanges per hour
Ideally in closed cabinets
As long as the sterile wrap remains sealed, undamaged and dry, internal sterility should be maintained indefinitely

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What should you label your sterilized pack with?

Instrument types
Sterilization date
Expected expiration date
Name/initials of staff who sterilized

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After autoclaving, small instruments in double wrapped linen or double pouched are sterile for how long with appropriate storage?

96 weeks (24 months / 2 years)

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After EtOx sterilization, how long are heat-sealed plastic wrapped items sterile for?

12 months

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Define sterilization.

Destruction of all microorganisms including bacteria, viruses, fungi, spores, and prions.

Define sterility assurance level (SAL).

Probability of a single viable microorganism occurring on a product after sterilization.

Define cleaning.

Removal of gross debris.

Define decontamination.

Removal of sufficient microbes to render equipment safe to handle or discard.

Define high-level disinfection.

Kills all microorganisms except large numbers of bacterial spores.

Define intermediate-level disinfection.

Kills most vegetative bacteria and some fungi and viruses but not spores.

Define low-level disinfection.

Kills most vegetative bacteria and some fungi and viruses.

What are examples of critical items.?

Surgical instruments, implants, needles, catheters.

What are examples of semi-critical items.?

ET tubes, laryngoscopes, esophageal probes.

What are examples of noncritical items.?

Stethoscopes, blood pressure cuffs.

Why remove organic debris before sterilization?

Debris blocks sterilant contact and promotes biofilm formation.

Why use cool water initially?

Prevents protein coagulation.

Why disassemble multipiece instruments?

Ensures sterilant access to all surfaces.

What is the preferred cleaning method.?

Mechanical cleaning.

What is the mechanism of ultrasonic cleaning.?

Cavitation from imploding gas bubbles removes debris.

What is risk of inadequate rinsing after cleaning.?

Residual detergent contamination; risk of toxic anterior segment syndrome in ophthalmology.

What is environmental requirements for wrapping area.?

Controlled temperature, humidity, airflow; restricted access; clean attire.

What is the preferred wrapping technique.?

Double-layer wrapping.

What is indicator placement in packs.?

Internal indicator inside pack before wrapping.

Why open hinged instruments before sterilization?

Ensures sterilant penetration.

How to place pouches in autoclave?

On edge to allow steam contact.

Why avoid paper with hydrogen peroxide plasma?

Absorbs hydrogen peroxide.

What is the mechanism of steam sterilization.?

Moist heat causes protein coagulation and denaturation.

What is an advantage to prevacuum steam sterilization over gravity-dependent?

Removes air before steam; rapid uniform penetration.

What are the common causes of wet packs.?

Overloading, improper loading, insufficient absorbent material, inadequate cooling.

Why place bowls upside down?

Prevents air trapping.

Does steam sterilization kill spores?

Yes.

What are the parameters met by immediate use steam sterilization?

135°C for ~3 minutes plus short drying.

What is indication for immediate use sterilization.?

Emergency use only.

What is contraindication for immediate use sterilization.?

Implants.

What are the parameters for dry heat sterilization?

160°C for 120 minutes.

When is dry heat preferred?

Sharps, powders, glassware.

Why is cold sterilization not true sterilization?

Lacks sterility indicators; high-level disinfection only.

What is the minimum concentration of glutaraldehyde.?

1–1.5%.

What is glutaraldehyde shelf life.?

About 14 days.

What are the risks of glutaraldehyde use?

Irritates skin, mucosa, lungs.

What are the advantages of oPA (Ortho-phthalaldehyde) use?

Less irritating; no pH adjustment required.

What is hydrogen peroxide effective concentration.?

>7.5%.

What is hydrogen peroxide mechanism.?

Hydroxyl free radicals damage membranes and nucleic acids.

What is peracetic acid concentration.?

0.2%.

What is peracetic acid shelf life.?

Approximately 6 days.

What is ethylene oxide mechanism.?

Alkylates proteins and nucleic acids.

What is ethylene oxide indication.?

Heat-sensitive items.

What is ethylene oxide hazards.?

Toxic, mutagenic, carcinogenic.

Why is aeration required after EtO?

Absorbed into plastics and rubber.

What is biologic indicator for EtO.?

Bacillus atrophaeus.

What is ozone mechanism.?

Oxidation of cellular components.

What is ozone parameters.?

30–35°C for ~4 hours.

What is ozone contraindications.?

Wood and paper.

What is plasma sterilization mechanism.?

Electromagnetic energy creates hydrogen peroxide plasma producing free radicals.

What is plasma parameters.?

40–50°C for 28–75 minutes.

What is plasma packaging requirement.?

Synthetic materials only.

What is biologic indicator for plasma.?

Geobacillus stearothermophilus.

What is vaporized hydrogen peroxide contraindications.?

Liquids, linens, powders, cellulose.

What is advantage of vaporized hydrogen peroxide.?

Low temperature; rapid; environmentally safe.

What is radiation sterilization source.?

Cobalt-60 gamma rays or electron accelerators.

What are the common use of radiation sterilization.?

Implants and sutures at manufacturer level.

What is best indicator of sterilization efficacy.?

Biologic indicators.

What is class 1 indicator.?

External exposure indicator (tape).

What is class 2 indicator.?

Bowie-Dick test (air removal).

What is class 3 indicator.?

Single parameter.

What is class 4 indicator.?

Multiple parameters.

What is class 5 indicator.?

Integrating; reacts to all critical parameters.

What is class 6 indicator.?

Emulating; cycle-specific parameters.

What is recommended chemical indicator placement.?

Class 1 outside; one additional internal indicator.

What is biologic indicator organism for steam.?

Geobacillus stearothermophilus.

What is frequency of biologic testing.?

Ideally weekly.

What is the storage temperature requirement.?

<24°C (75°F).

What is the storage humidity requirement.?

<70%.

What is ideal storage location.?

Closed cabinets; dry; dust-free; away from sunlight.

What is the shelf life double-wrapped autoclaved packs.?

Approximately 96 weeks.

What is the shelf life eto cloth.?

15–30 days.

What is the shelf life eto paper.?

30–60 days.

What is the shelf life eto plastic sealed with tape.?

90–100 days.

What is the shelf life heat-sealed plastic.?

1 year.

Chapter 11 - Sterilization Flashcards

(99 cards)