Decontamination appropriately purified.
l Pure steam generators should be designed, qualified, and operated in a manner to ensure that the quality of steam produced meets defined chemical levels.
l The steam used as a direct sterilising agent should be of suitable quality and should not contain additives at a level which could cause contamination.
l For a pure steam generator supplying pure steam used for the direct sterilisation of materials (e.g. porous hard-good autoclave loads), the steam condensate should be periodically tested meet to show chemical purity, non-condensable gases, dryness value (dryness fraction) and superheat.
These various factors need to be evaluated by a validation exercise. The steps to qualify an autoclave typically require: l Heat distribution qualification in the empty chamber (OQ).
l Heat distribution qualification in the loaded chamber (PQ) where the composition and means of containment and manner of packing of the load has been precisely defined.
l Heat penetration qualification into loads within the chamber (PQ).
l For this assessment thermocouples are used and temperature charts generated.
l This is followed by biological kill validation (‘biovalidation’).
The validation, as a minimum, should be performed under worst case conditions of temperature and time. For the biovalidation stage, endospores of a heat resistant organism,
of a suitably high population, are required. The most common organism used (although it is not the only one that can be selected) is the thermophilic bacterium Geobacillus stearothermophilus. Gs. stearothermophilus is often preferred due to its resistance to moist heat and it can be provided with a spore population in excess of one million, which means it can be used to demonstrate a Sterility Assurance Level of 10-6. Therefore, the probability of microbial survival
(or of there being one non-sterile unit) is one in one million. It therefore idicates the inactivation of highly resistant microorganisms, as well as less resistant organisms, including most pathogens.4 When used routinely, when running porous
cycles (hard goods) the parameters of time, temperature and pressure should be used to monitor the sterilisation process. Each item that has been sterilised should be inspected for damage, packaging material integrity and moisture on removal from the autoclave. Any item found not to be fit for purpose should be removed and, ideally, an investigation performed into the autoclave operation.
When autoclaves fail Wet loads: The presence of moisture on an item that has been autoclaved is an indicator of the probable failure of the sterilisation process. Some scenarios for wet loads include:5 l Visible moisture on outside of packs. l Moisture inside pack (e.g. moist towel). l Visible water inside the tray containing the load.
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www.clinicalservicesjournal.com I November 2024
Senalfred -
stock.adobe.com
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