Monitoring sterilizers—part I


Sterilizer monitoring is an essential part of any reprocessing program as it verifies that the sterilizer is working and that conditions to achieve sterilization have been met. Requirements for sterilizer monitoring include physical monitors, chemical indicators and biological indicators.

  1. Physical monitoring
    Physical monitoring is the process of verifying and recording the sterilizer cycle time, temperature and pressure displayed by the sterilizer during each load (reprocessing cycle). Physical monitoring is displayed through a sterilizer printout or, if the sterilizer does not have a printout, is obtained by visually monitoring and recording the sterilizer gauge parameters during the sterilization cycle. Note: When purchasing a new or replacement sterilizer, the sterilizer must have a printout/record. The sterilizer printout/record must be reviewed to ensure that the correct time, temperature and pressure were achieved for each load. Incorrect readings may be the first indication that a problem has occurred with the sterilization cycle.

  2. Chemical indicators
    Chemical indicators are used both inside and outside of each package and indicate that the package has been processed though a sterilization cycle. The chemical indicator will change colour when the sterilizer parameters have been met. If the chemical indicator fails to change colour, this reveals a problem and therefore the instrument load should be re-packaged with new chemical indicators and re-sterilized.

  3. Biological indicators
    Biological indicators (BI) provide direct evidence that the sterilization process conditions were sufficient to kill spores. A biological indicator is run at least every day the sterilizer is used, every time the cycle is changed on the sterilizer, e.g. gravity, pre-vac, and in all loads containing implants. Following the manufacturer’s instructions for use, a BI is run through a sterilization cycle and then placed in a BI incubator. Once incubated for the timeframe specified by the manufacturer’s instructions for use, the BI is read. A positive BI indicates that sterilization was not achieved. In the event of a positive BI, non-hospital facilities are requested to contact the program staff for further guidance.

All three types of monitors (physical, chemical and biological) are required to confirm that the conditions necessary to achieve sterility have been met. Therefore, before using the sterilized medical devices/instruments on a patient, the physical monitoring, chemical indicators and biological indicators must be reviewed and verified to ensure that all parameters have been met.

For further information on instrument and equipment sterilization, please refer to the Best Practice Guidelines for Cleaning, Disinfection and Sterilization of Critical and Semi-critical Medical Devices issued by the Ministry of Health. 

Watch for part II in a future edition of the College Connector to read more about what to do when sterilizer monitoring results indicate sterilization failure.