Sterilization Flashcards
Sterilization:
High Temp: Steam and Dry Heath
Low Temp: Ethylene Oxide, Hydrogen Peroxide Gas Plasma, Peracetic Acid
Ethylene Oxide:
The concept of sterility is measured as a probability of sterility for each item to be sterilized.
This probability is commonly referred to as sterility assurance level (SAL) of the product as is defined as the probability of a single viable microorganism occurring on a product after sterilization.
SAL is normally expressed a 10-n
SAL is an estimate of lethality of the entire sterilization process and is a conservative calculation.
High Temp Sterilization:
Subjecting items to thermal energy from moist heat (steam) or dry heat.
Steam is the most frequently used sterilant for devices that are not heat-sensitive because of its successful record of safety, efficacy, reliability, and low cost.
Steam sterilization leaves no chemical residues or byproducts.
Dry heat sterilization is rarely used because of lengthy exposure times.
Sterilization cannot be achieved if an instrument or device has not been thoroughly cleaned.
Bioburden can act as a shield on instruments and make it difficult for sterilization.
Four Parameters:
1. Steam (Moisture)
2. Pressure
3. Temperature
4. Time
The most common steam-sterilizing temperatures are 121 c (250) and 270.
Two main type of steam sterilizers:
Gravity displacement sterilizer 250
Dynamic air removal sterilizer Temp 270-275
Gravity temp < Steam
Gravity cycles typically require more exposure time because the air removal method is more passive in nature. Temp usually 250. Sterilization cycles will depend on what you are putting in your sterilizer.
Dynamic air removal Sterilizers- advantage instantaneous steam penetration
Immediate use Steam Sterilizers “Flash” sterilization
Sterilization of unwrapped object at 270.0 for 3 minutes at 27-28 lbs of pressure in a gravity displacement sterilizer.
Items must be approved by manufacturer. Items need to be used immediately after sterilization cycle- cannot be stored for a later time.
Not recommended as a routine sterilization methods because of the lack of timely biological indicators to monitor performance, absence of protective packaging following sterilization, possibility of contamination of processed items during transportation to the operating rooms and sterilization cycle parameters (time, temp, pressure) are minimal.
Low Temp Sterilization:
Typically used to sterilize unique devices with complex designs and/or those made of heath and moisture sensitive materials including fiber optics, polymers or cameras, flexible scopes, certain plastics that cannot withstand the heat and moisture associated with team sterilization.
Chemicals may have toxic properties- important to know the safety recommendations.
Each method has pros and cons.
What is the preferred method for sterilization:
Steam however not all instruments may be sterilized this way.
The permissible exposure limit (PEL or OSHA PEL) is a legal limit the US for exposure of an employee to a chemical substance physical agent such as high level noise.
Time weighted average is the amount of exposure to a physical chemical agent over a work shift.
ETO Ethylene Oxide T= Toxic and Too much Time (8 hours)
Classified as Toxic gas- > carcinogen and reproductive
ETO comes in cartridges that get placed inside of the chamber.
Cycle takes approximately 2.5 hours
Must go through an aeration cycle that can take 8-12 hours to ensure all the ETO is removed.
ETO can stay on instruments and cause issues.
Prevents normal cellular metabolism and replication
ETO inactivates all microorganisms although bacterial spores (B atrophaeus) are more resistant than other microorganisms; hence, it is the recommended biological indicator.
ETO is colourless gas that is flammable and explosive.
Linked to hematological changes and increased risk of spontaneous abortions.
Hydrogen peroxide Gas Plasma
Fourth state of matter- plasma.
Hydrogen peroxide solution ranging from 59%-95%
Why is it popular?
Much safer
Rapid cycle times
faster turnaround time for medical devices
By product of the cycle (water vapor, oxygen) are nontoxic and eliminate the need for aeration. Thus, sterilized materials can be handled safely, either for immediate use or storage.
May sterilize: single channel flexible endoscopes, cameras, rigid endoscopes, light cameras, batteries, power drills.
Not compatible with: liquids or powders, any material that absorbs liquids, items that contain cellulose (linen, towels, etc)
Time 28-75 minutes
Excess moisture on devices can cause the cycle to abort.
Vaporized hydrogen peroxide - Not approved
Rapid cycle time
low temp
environmentally safe
Ozone Sterilization
creates sterilant internally-> USP grade oxygen, team quality water and elecricity. Converted back to oxygen and vapor at the end
Duration 4 hours 97C
SAL= 10 to the 6
Most resistant organism: Geobacillus stearothermophilus
