UNDERSTANDING POUCHES AND CHEMICAL MONITORING

mechanical, chemical and biological monitoring
According to CDC guidelines best practices for sterility assurance include a combination of mechanical, chemical and biological monitoring.  Combined, these parameters evaluate both the sterilizing conditions and the procedure’s effectiveness. The first monitoring tool is mechanical monitoring, which includes assessing cycle time, temperature, and pressure by observing the gauge, digital displays, or printout on the sterilizer and noting these parameters for each load. Reminder: A correct end point response does not ensure sterilization, but incorrect readings can be the first indication of a gross equipment malfunction.

Chemical monitoring

Chemical monitoring requires utilization of external and internal chemical indicators that use color change inks to assess one or more physical conditions/parameters/variables (i.e. time, temperature, sterilant) during the sterilization cycle. 

External indicators – are used outside of a pack and verify that the package has simply been EXPOSED to the sterilization process.  The most basic example of an external indicator is steam indicator tape (autoclave tape).  This type of Class I process indicator provides a definitive color change (i.e. white to black) when exposed to heat. 

Internal indicators – are used inside a pack and ensure the sterilant has PENETRATED the package and actually REACHED the instruments inside.  Internal indicators can be single-parameter or multi-parameter.  Multi-parameter indicators require two or more parameters (time, temperature, sterilant) to reach their stated end point color change. 

The CDC Guidelines for Infection Control in the Dental Healthcare Setting (2003) states “Internal chemical indicators should be used inside each package to ensure the sterilizing agent has penetrated the packaging material and actually reached the instruments inside. A single-parameter internal chemical indicator provides information regarding only one sterilization parameter (e.g., time or temperature). Multi-parameter internal chemical indicators are designed to react to >2 parameters (e.g., time and temperature; or time, temperature, and the presence of steam) and can provide a more reliable indication that sterilization conditions have been met.”

To summarize, chemical indicators provide information about sterilization conditions on the outside and inside of each package. Although they do not prove sterilization has been achieved, they allow for detection of certain equipment malfunction, and can help identify procedural errors, such as overloading or incorrect cycle selection. 

PACK VS. LOAD MONITORING
The aforementioned paragraph helps explain the difference between PACK monitoring and LOAD monitoring. Chemical indicators monitor each individual pack/package; whereas biological indicators monitor the load. So it is extremely advantageous to use chemical indicators as it allows you to single out individual packs that weren’t exposed to sufficient sterilization parameters. So if your load passes biological testing, but your chemical indicator on a pack fails…you only need to recall and reprocess the pack.