Chemical Indicator Classifications

When considering which class of indicator to use, you must consider your external and internal chemical monitoring needs for your various sterilization systems.

External indicators are simply used to distinguish between processed and unprocessed items. A Class 1 indicator in the form of tape, an indicating label, or the indicator legend on a paper or plastic peel pouch is appropriate and should be placed on each package that is intended for sterilization. The external CI usually exhibits a simple visual color change that shows the package has been exposed to physical conditions present during a sterilization process.

Internal indicators need to be used within each package that will be sterilized. Depending on the complexity of the pack and devices within them, a Class 3, Class 4, or Class 5 CI can be used. All internal CIs should be placed in an area of the package that is determined to be the least accessible to sterilant contact. This may not always be in the center of the package. AAMI states that a Class 5 indicator may serve as the basis for the release of processed items, excluding implants. Integrator challenge packs utilize a Class 5 chemical integrator within an appropriate challenge pack to monitor sterilization loads. The challenge packs are placed within the sterilization load, outside the packs, in the sterilization chamber, and have been correlated to the kill achieved in the AAMI 16 towel BI test pack. The result of the chemical integrator may be used to release the load, excluding implantable devices. Results of external indicators and chemical integrator challenge packs can be read at the end of the sterilization cycle when the package is retrieved from the sterilizer. However, internal indicators must be interpreted at the time of use. Therefore all healthcare personnel should be trained on the proper interpretation of a positive and negative result and what to do if a negative result occurs.