Basic Check Points Of Autoclave Validation

The success of sterilization is dependent upon the performance reliability of the autoclave. Validation of effectiveness includes monitoring temperature, pressure and cycle duration time for each cycle and providing periodic sterilization/decontamination challenges (quality assurance), i.e. use of biological indicators. A logbook should be maintained to record autoclave use and be available for inspection.

Temperature: This denotes the heat produced inside an autoclave using saturated steam under a pressure of approximately 15psi to achieve a chamber temperature of a least 121°C (250°F) for a minimum of 30 minutes. 

Time: Adequate autoclaving time is a minimum of 30 minutes, measured after the temperature of the material being sterilized reaches 121 degrees C and 15psi pressure. 

Contact: Steam must contact all areas of the load. Autoclave bags should be left partially open during sterilization/decontamination to allow steam to penetrate into the bag. Air pockets or inadequate steam supply will cause sterilization failure. 

Containers: Properly select and use leak-proof containers for items to be autoclaved. Make sure plastic bags and pans are autoclavable, to avoid having to clean up melted plastic. Plastic bags should specify on the label that they can be autoclaved. 

•  Primary Containers: Autoclave bags come in a wide variety of sizes and colors. They are usually placed in a secondary container during decontamination cycles to catch liquids that may drain out of the bag.

• Secondary Containers: Plastic or stainless steel containers are commonly used to contain material during autoclaving. Polypropylene plastic pans with 6-12 inch sides are favored over polyethylene and polystyrene because it can withstand autoclaving without melting. Stainless steel containers are durable and good conductors of heat.

Indicators: This term refers to the tools used to validate the sterilization/decontamination process. The most common type of indicator that is used in laboratories is autoclave tape. Tape indicators can only verify that the autoclave has reached normal operating temperatures for sterilization/decontamination, and have no time factor. Most chemical indicators change color after being exposed to 121 degree C, but cannot measure the length of time spent at 121 degrees C. Biology indicators (such as Bacillus stearothermophilus spore strips) and certain chemical indicators (such as Sterigage) verify that the autoclave reached adequate temperature for a long enough time to kill microorganisms.  

Moisture: Steam saturation is essential for maximum heat transfer. Air pockets or inadequate steam supply will cause sterilization failure.