Steam Sterilization: Autoclaving


Autoclave An autoclave is a self locking machine that sterilizes with steam under pressure.
Sterilization is achieved by the high temperature that steam under pressure can reach.
The high pressure also ensures saturation of wrapped surgical packs.

Autoclave Settings Temperature (F) Pressure (PSI) Time (min)
General Wrapped Items 250 20 30
Bottled Solutions 250 20 30
'Flashing' 270 30 4-7

Preparation for sterilization

Wrapping and Indicators All instruments must be double wrapped in linen or special paper or placed in a special metal box equipped with a filter before sterilization.
'Flashing' is when an instrument is autoclaved unwrapped for a shorter period of time. 'Flashing' is often used when a critical instrument is dropped.

Color Change Sterilization Indicators

Indicators The white stripes on the tape change to black when the appropriate conditions (temperature) have been met.
Indicators should be on the inside and outside of equipment pack.
Expiration dates should be printed on all equipment packs.
Indicators Color indicators are also included on the outside and inside of equipment sterilized in paper packages.


Biological sterilization indicators contain spores that are supplied in closed containers and are included with the instrument being autoclaved. Inability to culture the spores after autoclaving confirms adequate sterilization. Biological indicators are the most accurate sterilization indicators.

Ethylene Oxide Sterilization: ETO Gas


Large Two-Chamber EtO Sterilizer

Ethylene Oxide Sterilizer Colorless gas, very toxic and flammable.
Requires special equipment
Odor similar to ether.
Used for heat sensitive instruments: plastics, suture material, lenses and finely sharpened instruments.
Materials must be well aerated after sterilization.
Materials/instruments must be dry.
This specific type of EtO sterilizer is only found in larger veterinary hospitals


Compact One-Chamber EtO Sterilizer
AnproleneŽ is the most commonly used EtO sterilizer in veterinary practices
Cartridges release 100% pure ethylene oxide
  Kills all known viruses,bacteria (including spores), and fungi
Annual safety inspections are recommended
For more information on the AnproleneŽ system, go to the commercial vendors section

Cold (Chemical) Sterilization:

Cold Sterilization Instruments must be dry before immersion.

Glutaraldehyde (Cidex) is the most common disinfectant.

3 hours exposure time is needed to destroy spores.

Glutaraldehyde is bactericidal, fungicidal, viricidal, and sporicidal.

Radiation Sterilization:

High energy ionizing radiation destroys microorganisms and is used to sterilize prepacked surgical equipment.
Used for instruments that can't be sterilized by heat or chemicals.
Radiation sterilization is being promoted as an alternative to ETO sterilization.
Care needs to be taken because not all materials can be irradiated successfully
Currently used by manufacturers, but not used in veterinary hospitals
Common sources of radiation include electron beam and Cobalt-60
For more information on specific sterilizers which utilize radiation, go to the commercial vendors section

Filter Sterilization:

Filter1.gif (31848 bytes) Filters are used for removal of microorganisms in fluids and gases. They come in a wide variety of types and sizes.
A 0.2 micron filter is required to remove bacteria from fluids.
The filter is placed in the IV line or on a syringe, so that the contaminated solution is sterilized before reaching the patient.


Gas Plasma:    

     Based on a patented process involving the generation of a low-temperature hydrogen-peroxide gas plasma
Recently on the market,  its efficiency in practice is still unproven
Requires only a 74 minute cycle time and leaves no toxic residues or emissions
Unlike EtO, it does not require special installation, ventilation, or aeration
Effectively sterilizes most heat- and moisture-sensitive medical devices and surgical instruments
For more information, go to STERRADŽ in the commercial vendors section