Steps of Dry-Heat Sterilization
- Step 1
- Decontaminate, clean, and dry all instruments and other items to be sterilized.
- Step 2
- Either 1) wrap the instruments and other items using foil, double-layered cotton, or muslin fabric; 2) put unwrapped instruments and other items on a tray or shelf; or 3) place instruments and other items in a metal, lidded container.
Note: Because dry-heat sterilization works by raising the temperature of the entire item to the designated temperature, it is not necessary to open or unlock hinged instruments or other items or to disassemble those with sliding or multiple parts. In addition, instruments and other items can be placed in closed containers.
- Step 3
- Place instruments and other items in the oven, and heat to the designated temperature. The oven must have a thermometer or temperature gauge to make sure the designated temperature is reached.
- Use the list here to determine the appropriate amount of time to sterilize instruments and other items for different temperatures. (do not begin timing until the oven reaches the desired temperature, and do not open the oven door or add or remove any items). The times shown here represent the amount of time that items must be kept at the desired temperature to ensure that sterilization is achieved. Keep in mind that the total cycle time--including heating the oven to the correct temperature, sterilization, and cooling--is usually twice as long as the time noted here.
170 degrees C (340 degrees F) - 1 hour
160 degrees C (320 degrees F) - 2 hours
150 degrees C (300 degrees F) - 2.5 hours
140 degrees C (285 degrees F) - 3 hours
- Note: Because dry heat can dull sharp instruments and needles, these items should not be sterilized at temperatures higher than 160 degrees C.
- Step 4
- Leave items in the oven to cool before removing. When they are cool, remove items using sterile pickups and use or store immediately.
- Step 5
- Store items properly. Proper storage is as important as the sterilization process itself:
- Wrapped items. Under optimal storage conditions and with minimal handling, properly wrapped items can be considered sterile as long as they remain intact and dry. For optimal storage, place sterile packs in closed cabinets in areas that are not heavily trafficked, have moderate temperature, and are dry or of low humidity. When in doubt about the sterility of a pack, consider it contaminated and resterilize it.
- Unwrapped items. Use unwrapped items immediately after removal from the autoclave or keep them in a covered, sterile container for up to one week.
Maintenance of ovens
If you use dry-heat sterilization at your facility, maintenance of dry-heat ovens should be part of every sterilization procedure. If the ovens do not reach the correct temperature, sterilization will not be achieved. Be sure to:
- Keep the oven clean.
- Check that the temperature gauge is working correctly on a regular basis--every few weeks is sufficient--by putting a thermometer in the oven and comparing the temperature reading with the one on the gauge.