SELF-STUDY SERIES CI Type Description
1 2
3 4 5
Process Indicator
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Used to show exposure to a process, no information provided about the quality of the process. Valuable for differentiating processed from unprocessed packs.
Specific Test Indicator Used in specific tests described in equipment and process standards, e.g. Bowie and Dick Test.
Single Variable Indicator Responds to one of the specified process variables e.g. temperature. Multivariable Indicators Respond to two or more of the specified process variables.
Integrating Indicators Respond to all of the process variables for a given sterilization process in a manner which mimics the response expected from an equivalent biological indicator. Also provide a result which directly relates to the minimum conditions required to achieve sterilization in any given process standard (see table 1).
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Emulating Indicators Respond to all of the process variables for a given sterilization process providing a result equivalent to the minimum sterilization conditions specified in a process standard (see table 1).
Table 2: The types of chemical indicators specified in international standard EN ISO 11140-1.
monitored. The standard also specifies the test conditions under which a fail response should be observed and these are related to a specified reduction in each of the Ss. Table 3 shows the exposure conditions for a pass and fail response for types 1 and 4 H2
type 4 CI are the same as for the type 1, and the table then illustrates the test conditions required for the CI to show a fail response. It should be clear from the information shown that a type 4 CI will have greater sensitivity towards process failures.
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Recent studies examining the performance of VH2
Two studies have recently been published examining the performance of some types and CIs. The first study7
O2 performance of eight CIs for H2
When tested according to the methods described in N ISO 0-, it was found that two of the type 1 CIs showed appro- priate pass and fail results. Another type 1 CI gave all passes and one all fails. Two of the type 4 CIs gave appropriate pass and fail results. Another type 4 showed slight differences in color in pass or fail tests and another type 4 gave the same pass color in all tests.
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ization processes to give a pass or fail result when tested according to the methods in N ISO 0- and also to detect changes in the individual process variables time, temperature and H2
examined the O2
steril- concentration. CIs CIs. In the eample the Ss for the In the second study8 the same CIs were
tested in two sterile processing depart- ments in S hospitals in order to eamine their performance when placed in four dif- ferent model loads, then processed in ster- ilization cycles which were recommended, and then when operated with unsuitable overweight loads or incorrectly selected sterilization processes. The ability to detect differences in sterilizing conditions within individual packs was also evaluated. The results indicated that not all of
sterilizer had not been used according to recommendations. Of the eight CIs tested, four were able to indicate the use of an incorrect loading configuration or use of an incorrect sterilization process. Two of these four were also capable of indicating non- uniformity of sterilizing conditions within individual model load packs. The results of these studies confirm the importance of using a range of monitoring systems, rather than relying on one, the information from which add to the overall assurance of process efficacy and load sterility.
the CIs were able to indicate if a H2 O2
processes are designed for a specified range of instruments and loads. It is vital that manufacturers’ recommendations are carefully followed. Failure to do so
Use of CIs during performance qualification Unlike steam sterilization, which provides a high overill, and wide utility, H2
O2 48 February 2021 • HEALTHCARE PURCHASING NEWS •
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has potential implications for the steril- ity assurance associated with a load and indicates the importance of conducting PQ studies when introducing new devices, sterile barrier systems or accessories into the wor flow in order to detect incompat- ibilities and potential processing problems, but also to establish the area of the pack that creates the greatest challenge to ster- ilant penetration, thereby informing the position of placement for routine moni- toring. In hospitals it can be difficult for practitioners to carry out PQ using inde- pendent PIs since introducing sensors into the sterilizer chamber require specialist expertise. Free-standing temperature log- gers, which are activated and then placed into the chamber, are available, however these can be epensive. However, can still be performed using CIs and BIs. The use of CIs within instrument sets can potentially detect process problems when conducting PQ studies to ensure a new load is compatible with the intended ster- ilization cycle. of H2
in national guidance documents.5 O2
Use of CIs during routine monitoring Sterilizer manufacturers will specify the loads which can be sterilized in each cycle programmed into the equipment and medical device manufacturers and will specify which types of sterilization process can be used to sterilize their
is discussed
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