Chemical indicator classes

Sterile processing definition

Chemical indicators are grouped into six classes under ISO 11140-1. Class 1 process indicators (like tape) show an item was processed. Class 2 is for specific tests such as the Bowie-Dick. Class 3 responds to one critical variable, Class 4 to two or more. Class 5 integrating indicators respond to all critical variables and correlate with biological indicator performance. Class 6 emulating indicators respond to all variables for a specific cycle.

On the CRCST exam

Expect questions on which class does what, especially Class 1 versus Class 5.

Exam domain: Sterilization Process (about 21% of the exam)

Sterilization Process practice questions

The conditions steam sterilization needs
Prevacuum steam cycle time and temperature
Wet packs after steam sterilization
How to load basins in a steam sterilizer

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