Low Temperature Low Temperature SterilizationSterilization

Chapter 16

Objectives:Objectives:As a result of successfully completing this

chapter, students will be able to:Discuss basic requirements important for any

type of low temperature sterilization systemExplain specific requirements for the three low

temperature sterilization methods: ethylene oxide, hydrogen peroxide (gas plasma), and ozone

Review (compare) important parameters of the three low temperature sterilization methods commonly used by health care facilities

Basic Sterilization RequirementsBasic Sterilization Requirements

EffectivenessSafetyMonitoringQuality AssurancePenetrationMaterial CompatibilityAdaptabilityApproval

Ethylene OxideEthylene Oxide

Used commonly in Hospitals since the 1960s

Excellent Penetration Capabilities

Kills microorganisms by alkylation

AlkylationAlkylation

The process of destroying microorganisms by making the cell

unable to metabolize and/or reproduce

Ethylene Oxide Process Ethylene Oxide Process ParametersParameters

Time

Temperature

Concentration of EtO

Relative Humidity

TerminologyTerminology Residual- The amount of EtO that remains inside of materials

after they have been sterilized Aeration- A process in which a device is actively subjected to

moving air. For example, items that have been sterilized with EtO

Sterility Assurance Level (SAL)- The probability of a viable microorganism being present on a product after sterilization

Permissible Exposure Limits (PELs)- Limits developed by OSHA to indicate the maximum concentration of a contaminant to which an employee may be exposed over the duration assigned to that contaminant

Time Weighted Average (TWA)- The employee’s average airborne exposure in any 8-hour work shift of a 40 hour work week

Parts Per Million (PPM)- Parts Per Million (PPM) is the term used to measure the volume of gas in a vapor

EtO SystemsEtO Systems

100% EtO

Gas Blends

Employee SafetyEmployee SafetyEmployees should receive instruction on:

◦ Hazards of EtO◦ Procedures to reduce employee exposure◦ Principles of EtO monitoring and interpretation of results◦ Use of protective equipment◦ OSHA Standards◦ MSDS Sheets◦ EtO Emergency Plans◦ Processing procedures◦ Storage and handling of EtO gas containers

EtO SafetyEtO SafetyEtO is a Toxic Gas

EtO Sterilizers should be located in a well-ventilated area with a room air exchange rate of 10 air exchanges per hour

Additional information about EtO safety is included in Chapter 21, Safety, pages 405 – 408 of the text

Personnel Personnel MonitoringMonitoring

Personal devices worn with 1 foot of the employee’s breathing zone◦Provide delayed results

Area monitors continuously monitor airborne EtO◦Provide real-time information

Education Should also include:Education Should also include:

Specific training from the manufacturers of the gas containers and the sterilizer

Aeration of EtO Sterilized Aeration of EtO Sterilized ItemsItems

Minimum recommendations for aeration:

◦8 hours at 1400F (600C)

◦12 hours at 1220F (500C)

*Some items require significantly longer aeration. Consult device manufacturer’s recommendations for specific guidelines

Loading the EtO SterilizerLoading the EtO Sterilizer Do not overload

When possible use metal carts or baskets

Do not let items come in contact with chamber walls

Place peel pouches on edge

Do not stack items on top of one another

Unloading the EtO SterilizerUnloading the EtO Sterilizer If possible aerate before

handling

When transferring loads to the aerator, pull, don’t push the load

Follow your specific facility's safety protocols

Once a load has been placed in the aerator, new groups of sterilized items should not be added

EtO Sterilizer Performance EtO Sterilizer Performance MonitorsMonitors

Physical Monitors (Charts, Printout Tapes and Graphs

Chemical Indicators

Biological Indicators (Bacillus atrophaeus)

Hydrogen Peroxide (Gas Plasma)Hydrogen Peroxide (Gas Plasma) Popular because of its short cycle

times Uses H2O2 vapor and low

temperature gas plasma doe rapid inactivation of microorganisms

Is widely compatible with different materials

Is not compatible with powders and strong absorbers like paper and linen made of cellulose

There are some restrictions regarding the sterilization of lumens (diameter and length). Consult device manufacturer recommendations for specific parameters

Staff Safety Education:Staff Safety Education:

Hazards of H2O2

MSDS Sheets

OSHA PEL

Process for changing vapor plates

Storage, handling and disposal of cassettes

MonitoringMonitoring

Physical Monitors (Printout)

Chemical Indicators

Biological Indicators (Geobacillus stearothermophilus)

OzoneOzoneNewest low temperature

processNo purchase of sterilant

needed. The system generates the O3 needed

Process parameters:◦Time◦Temperature◦O3 Concentration◦Relative Humidity

Overview of Low Overview of Low Temperature ProcessesTemperature Processes

A comparison chart of the low temperature sterilization methods covered in this unit is located on page 341 of the text.