STERILIZATION

The methods of sterilization in common use are:

Autoclaving should be the main form of sterilization at the district hospital.

Autoclaving
Before sterilizing medical items, they must first be disinfected and vigorously cleaned to remove all organic material. Proper disinfection decreases the risk for the person who will be cleaning the instruments. Sterilization of all surgical instruments and supplies is crucial in preventing HIV transmission. All viruses, including HIV, are inactivated by steam sterilization (autoclaving) for 20 minutes at 121°C–132°C or for 30 minutes if the instruments are in wrapped packs.

For efficient use, an autoclave requires a trained operator and depends on regular maintenance. The selection of a suitable autoclave requires serious consideration not only of the cost, but also:

In general, the smaller the capacity, the shorter the whole process and the less damage to soft materials. It is often more practical to use a small autoclave several times a day than to use a large machine once.

Appropriate indicators must be used each time to show that sterilization has been accomplished. At the end of the procedure, the outsides of the packs of instruments should not have wet spots, which may indicate that sterilization has not occurred.

Dry heat
If items cannot be autoclaved, they can be sterilized by dry heat for 1–2 hours at 170°C. Instruments must be clean and free of grease or oil. However, sterilizing by hot air is a poor alternative to autoclaving since it is suitable only for metal instruments and a few natural suture materials.

Boiling instruments is now regarded as an unreliable means of sterilization and is not recommended as a routine in hospital practice.

Antiseptics
In general, instruments are no longer stored in liquid antiseptic. However, sharp instruments, other delicate equipment and certain catheters and tubes can be sterilized by exposure to formaldehyde, glutaral (glutaraldehyde) or chlorhexidine.

If you are using formaldehyde, carefully clean the equipment and then expose it to vapour from paraformaldehyde tablets in a closed container for 48 hours. Ensure that this process is carried out correctly.

Glutaral is a disinfectant that is extremely effective against bacteria, fungi and a wide range of viruses. Always follow the manufacturer’s instructions for use.

Failure of normal methods of sterilization
Failure of an autoclave or a power supply may suddenly interrupt normal sterilization procedures. If an extra set of sterile equipment and drapes are not available, the following “antiseptic technique” will allow some surgery to continue.