Objective: To assess whether ISO 11140 part 1 class 6 Chemical Indicators (CIs) for steam sterilization actually meet their claimed Stated Values (SVs). SVs for steam sterilization represent a temperature-time combination at which the CI has to give an unambiguous pass result, e. g. at 134°C after 3.5 minutes in saturated steam. Design: Six types (brands) of commercially available ISO 11140 part 1 class 6 CIs were purchased and investigated. These CIs were exposed to saturated steam at 134°C. The exposure time was varied from 1 s to 15 minutes. At the SVs of the indicator it has to show an unambiguous color change towards the reference color. This color change indicates a pass result. Method: After exposure of the CI s to saturated steam the indicator ink and the reference color on the CI strip were read out immediately. To avoid observer-dependent results these readings were obtained from a spectrodensitometer. Results: Only one type of the six class 6 CIs actually reached its reference color and showed a color change close to its SVs. Conclusions: Class 6 CIs have only a very limited added value and in most cases their use may lead to conclusions that are unreliable and even unsafe.
|Number of pages||10|
|Journal||Zentralsterilisation - Central Service|
|Publication status||Published - 1 Dec 2012|