The Principles of Medical Device Decontamination

It should be a universal step in endoscope reprocessing. In no case does it have to be an exacting process, all that needs to occur is the removal of most of the visible contamination or equivalent processes for hidden contamination such as that within devices with lumens. Here failures are likely to be sporadic. For surgical instruments, these should be identified on post washer-disinfector inspection. Failures with endoscopes will be more difficult to identify. Surgical instruments washer-disinfectors (SIWDs): These use aqueous-based mechanical processes to clean (using detergents) and thermal, as opposed to chemical, disinfection for surgical instruments prior to inspection, packing, and sterilisation. Steam sterilisation, considered in more detail later, is a process with a very high safety margin and very unlikely to be compromised by cleaning failures. The heat disinfection is intended to inactivate the pathogens which present a risk to SSD staff who handle the instruments in the clean room. The parameters used (equivalents to 90 o C for 1 minute) have a high safety margin. Minor failures will not be a safety issue; major failures could expose SSD staff to risk but will not compromise steam sterilisation of the device itself. The chemical quality of the water in all stages of the SIWD cycle is for preservation of instrument quality and allows optimum efficacy of process chemicals. Failures here are of minor significance and very unlikely to impact patient safety. [The occasional post SIWD bioburden testing that is required for accreditation is part of a more general quality assurance system and does not reflect on patient safety]. This testing just gives bacterial numbers on a very small number of washer-disinfector processed items. It does not establish the resistance of those contaminants to the sterilisation process (bacterial spores will be vastly more significant than vegetative bacteria) nor do the findings alter the sterilisation parameters. The standard steam sterilisation cycles involve a very high degree of overkill that will not be compromised by the minor variations in microbial challenge. EWDs use chemical disinfection, which is less robust than SIWD’s heat disinfection, and it is very unusual for the process to be followed by terminal sterilisation. (The British Society of Gastroenterology (BSG) do recommend sterilisation of endoscopes used in certain procedures which are listed in their guidance documents. This will also apply to other (non-gastrointestinal) endoscopes when used surgically i.e. enter

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