Thorough drying has been shown to reduce the risk of microbial contamination following high-level disinfection from the recontamination of the endoscope by waterborne microorganisms during rinsing. The presence of these microorganisms in conjunction with retained moisture can lead to the development of biofilm and increase patient infection risks. Recent research has led to many revisions to ST91’s drying recommendations after completion of the cleaning and disinfection process. Based on evidence, it is recommended that endoscope channels be dried for a minimum of 10 minutes with pressure-regulated forced instrument air (or, at minimum, HEPA-filtered air). If moisture is still observed, the drying time should be extended until no moisture is visible. The endoscope manufacturer’s written IFU should be reviewed for the maximum PSI. Note: Manual drying should occur even if an AER is used and it has an air purge or extended dry time feature.
The use of alcohol has long been recommended in the drying process after disinfection is completed; however, some studies have shown that alcohol can be a fixative agent. For that reason, ST91 now recommends that a multidisciplinary team (with representation from infection preventionists, endoscopy and perioperative nurses, endoscope processing personnel, endoscopists, and other involved personnel) conduct a risk assessment to determine whether endoscope lumens should be flushed with 70% to 90% ethyl or isopropyl alcohol.
Additional language was added to the ST91 section, Terminal sterilization by gaseous chemical sterilization processes. Sterilization of endoscopes is recommended because sterilized endoscopes provide an increased safety margin over HLD-processed endoscopes. Terminally sterilized endoscopes are completely dry and packaged (thereby reducing the chance of contamination for longer periods of time), and patient-ready. Packaged endoscopes have tamper-evident seals that clearly distinguish used endoscopes from “patient-ready” endoscopes.
New recommendations were also added regarding the storage of liquid chemically sterilized endoscopes. Liquid chemically sterilized endoscopes intended for use as critical devices should not be stored with a claim as being patient-ready; instead, they should be used immediately after processing. They may also be used immediately in semi-critical applications. If endoscopes are processed using a liquid chemically sterilization method but are not meant for immediate use, they can be stored in the same manner as those that under HLD.
Author: Susan Klacik, Clinical Educator, HSPA
Source: https://array.aami.org/content/news/closer-look-st91-2021-endoscope-processing