Sterilization of surgical equipment is a vital aspect of aseptic technique. Some disposable materials such as suture or scalpel blades are available already sterilized. Reusable materials such as surgical instruments have to be sterilized prior to use.
It is important to thoroughly clean instrumentation prior to sterilization. Biological debris cannot readily be penetrated by sterilizing agents. There are several commercially available cleaning supplies for surgical instruments which can aid in the removal of debris. Soaking instruments in an appropriate detergent solution and then scrubbing them provides adequate cleaning in most situations. Ultrasonic cleaners may be used to dislodge debris that is difficult to remove.
There are many different methods of sterilization including wet or dry heat, chemicals and irradiation. Some of the most common and readily available approaches are discussed below.
Autoclave
Autoclaves use a combination of heat, steam and pressure to achieve sterilization. A specific temperature, pressure and duration of time are required, and may vary according to the type and size of material being autoclaved. A typical autoclave setting is 250° F at 20 psi for 30 minutes. When packing instruments for autoclave sterilization a temperature or biological indicator is included in the pack. Packs should be loaded into the autoclave without stacking so that the steam will be able to reach all surfaces. Materials that are sensitive to heat or moisture cannot be autoclaved.
Bead Sterilizer
Bead sterilizers use dry heat to sterilize instruments. They have a well that is filled with glass beads. The beads are heated, and the tips of instruments can be inserted into the well. The instruments must be wiped clean before they are placed in a bead sterilizer. It is important not to leave the instruments in the well for too long, or the instrument handles will become hot enough to cause a burn. It is also important to allow the instrument tips to cool down before they come in contact with an animal. The most common use for bead sterilizers is for between patients during multiple rodent surgeries.
Cold Sterilization
There are several commercially available cold sterilant chemicals, a few examples are listed below. Most contain gluteraldehyde which is available under several brand names. Surgical instruments can be stored in a solution of a cold sterilant, referred to as a cold tray. This method of sterilization is not considered adequate for any major surgical procedures, but can be used for minor procedures. It is important to read the product information for a chemical sterilant before using it. These chemicals will vary in contact time, safety precautions, efficacy and instrument compatibility. Instruments and supplies sterilized this way must be in contact with the chemical for at least the minimum contact time, and then rinsed with sterile water or saline to remove the chemicals prior to use to avoid irritating or damaging animal tissues.
Hydrogen peroxide/ plasma sterilization
Plasma sterilizers use a low temperature hydrogen peroxide vapor. This method is safe for most heat or moisture sensitive equipment. The necessary equipment for plasma sterilization is prohibitively expensive for an individual lab, or small facility. CSU’s Veterinary Teaching Hospital has a STERRAD® plasma sterilizer, and will process materials for a fee. Contact Central Services at 491-7104 or 297-1209 for more information.
Information from the manufacturer of the plasma sterilizer is available at:
http://www.sterrad.com/Products_&_Services/STERRAD/
Comparison Chart
*More information about sterilization can be found at:
http://www.roboz.com/catalog%20pdfs/Sterilization_and_Maintenance.pdf
Last updated July 7th, 2009