Ch 11 - Sterilisation Flashcards
What is the Spaulding classification regarding instruments for sterilisation?
- Critical - Associated with high risk of infection if they become contaminated as they come into contact with the bloodstream or sterile tissue
- Semi-critical - Come into contact with mucous membranes or non-intack skin
- Non-critical - Contact only intact skin
What is toxic anterior chamber syndrome (TASS)
Severe inflammation in the anterior chamber of the eye following ophtho procedures and seems to be related to instrument processing
What are the main options for cleaning of surgical instruments prior to sterilisation?
- 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
What is the only approvel method for drying instruments prior to steilisation?
Filtered, medical grade compressed air
What are the 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!
What is the most common wrap material? What are its downsides?
Cotton muslin wrap
- Can generate lint
- Not moisture resistant
- Requires a double layer
List the types of available sterilisation
- Liquid chemical germicides (cold sterilisation)
- Steam sterilisation
- Ethylene oxide sterilisation
- Ozone sterilisation
- Plasma sterilisation
- Vapourised Hydrogen Peroxide
- Sterilisation by radiation
Can Sterilised Elephants Only Produce Vegan Hippie Relatives
List some options for cold sterilisation. What are the problems with cold sterilisation
- Glutaraldehyde 1-1.5%
- Orthophthalaldehyde (Cidex)
- Hydrogen peroxide 7.5%
Should be considered high level disinfectants rather than sterilisation. Gluteraldehyde is irritation to skin and mms and can decrease pulmonary function. It is acidic and requires buffering prior to use. Cidex is less irritating and does not require a pH adjustment.
How do steam sterilisers work?
Kill microorganisms through coagulation and denaturation of proteins by moist heat
- Water serves as a catalyst and allows lower temperatures to be used
What are the 2 types of steam sterilisers?
- 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
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
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
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 can be damaged by moisture
What are the guidelines for flash sterilisation of a metallic, unwrapped, nonporous item in a gravity-displacement autoclave?
135C for 3min with 1min drying
What are the safety concerns surrounding ethylene oxide?
Carcinogenic, mutagenic and neurologic hazards
What is ozone sterilisation used for? What is the recommended temp and time?
- Good option for moisture and heat-sensitive items.
- 30-35C for 4 hours
What is plasma sterilisation?
- Use of electromagnetic energy to create a plasma phase from a vapour of hydrogen peroxide, oxygen or peracetic acid/h2o2mix
- Rapid and cost effective
- 45-59C for 28-75min
What is used for radiation sterilisation?
Cobalt 60 gamma rays or electron accelerators
What are the 6 classes of sterilisation indicators?
- Class 1 - Indicates the pack has been processes 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 that 1 parameter
- Class 5 - React to all parameters which are important for a certain type of sterilisation
- Class 6 - Monitor more specific guidelines for unique parameters eg combatting prior infection
Recommended to always use a class 1 indicator as well as an additional indicator in the deepest part of the pack
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
What are the ideal conditions for storage of sterilised materials?
- Temp should not exceed 24C
- Humidity should not exceed 70%
- 4 air exchanges per hour
As long as the sterile wrap remains sealed, undamaged and dry, internal sterility should be maintained indefinitely
