ETHYLENE OXIDE STERILIZATION (EtO)

This method is a low temperature sterilization method. Ethylene oxide kills microorganism through reaction toward microorganism’s DNA by alkilation mechanism. Toward health facility, ethylene oxide is usually used in the form of small container and in 100 % of concentration. Ethylene oxide is only used for tools which can not be sterilized by steam sterilization method. Four essential elements that must be noted in EtO sterilization are:
1. Gas concentration not less than 400 mg/liter
2. Temperature, not less than 36 C (cold cycle), not more than 60 C (warm cycle)
3. Relative humidity between 40%-100%
4. Time, directly correlating with the temperature and gas concentration, the higher the temperature and gas concentration, the faster of the sterilization process time.

Putting goods into Ethylene oxide sterilization machine
If possible, tools with the equal aeration time should be sterilized in the same time. When aeration is held separately and is not a part of a sterilization cycle, tools/goods can be moved to aeration machine using metal container, for metal doesn’t absorb EtO. The packing must be placed in the chamber in not too compact condition and not sticking the wall of the chamber.

Taking out goods from EtO Sterilization machine
The potential of EtO gas radiation toward health personnel can be minimized significantly when the procedure of taking out the goods is obeyed carefully.

EtO Sterilization Machine with Air Drainer (Purge)
Goods taken out immediately and aerated. In such condition the EtO concentration is in the minimum point. Pay attention to several things:
1.Never open EtO sterilization machine’s door when gas radiation phase is running. EtO modern machine usually equipped with a security mechanism to avoid the door opened when gas radiation phase is running.
2.Never open machine’s door if exhaust system doesn’t work optimally.

Minimizing EtO radiation toward health personnel
Can be achieved by:
1.Use sterilization machine with purge cycle system (draining) that will evacuate gas residue continuously until the machine’s door opened.
2.Use a special exhaust system so that the gas can be taken out outside the building.
3.Use a metal sterilization container to avoid direct handling of items or tools.
4.Make sure the personnel in charge has sufficient knowledge about EtO sterilization and its security awareness.