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IDI - Irish Decontamination Institute

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Central Service - Issue 2/2012

Central Service - Issue 2/2012

Central Service - Issue 2/2012


  • What's New in Standardisation: Technical Specification
  • Conflicting priorities in the healthcare system: 5th International Basel Symposium, 2 February 2012
  • 10th Sterilization Forum at University Hospital Munich
  • Rosemary Simpson


M. Steinmann, U.B. Rosenberg:
A Method for Quantification of the Cleaning Performance in the Ultrasonic Bath

Ultrasonic baths (ultrasonic cleaners) are used extensively in hospitals for (pre-) cleaning complex instruments in the Central Sterile Supply Department (CSSD) as well as at decentralised locations, e. g. for cleaning ophthalmologic instruments and endoscopic ancillary instruments.
Ultrasonic cleaning will also be the focus of a standardisation project to be carried out in the near future within the framework of EN ISO 15883.
Not all detergents are suitable for use in an ultrasonic bath. But to date there has been no method available in the instrument decontamination setting for reproducible measurement of the cleaning performance using a process challenge device (PCD) and test soil. It was possible only to check the functional capability of the bath by means of an aluminium foil test (1), a «SonoCheck» test (2) or, at most, by means of a hydrophone (3) or a cavitation energy meter (4). However, there was no way of investigating the action generated by the cleaning process on a concrete contaminant (soil).
Since ultrasonic baths are used in particular to clean complex instruments or poorly accessible surfaces, we set about finding an appropriate PCD. This is a 5-layer stainless steel mesh, in the form of discs with a 1 cm diameter and measuring 1.7 mm in thickness. Aliquots of 40 Ál reactivated sheep blood were applied to such discs. The discs were cleaned individually in glass bottles with a diameter somewhat larger than that of the discs. The glass bottles were always placed in the same position in the ultrasonic bath, using a perforated plate to immobilize them and assure reproducibility.
After cleaning residual soils were also extracted in the bottles in the ultrasonic bath. Thanks to the small extraction volumes, the sensitivity of the method is within an ideal range. To quantify the residual contamination, the orthophthalaldehyde (OPA) method was used.
With this newly developed test method it was possible to demonstrate the cleaning kinetics associated with different detergents. Under the chosen test conditions and on using detergents endowed with good activity, the cleaning course baseline (equilibrium) had been reached after around 5 min if no fixed blood was present. It was possible to demonstrate that the cleaning performance of a «biofilm cleaner» was inferior to that of an alkaline detergent and an enzymatic detergent. The alkaline detergent was most effective against heat-denatured blood. A non-fixing, aldehyde-free instrument disinfectant exhibited comparatively poor cleaning performance.
Finally, it was demonstrated that a high ultrasonic energy level is not to be automatically equated with a good cleaning performance.


D. Millner, P. Freitag:
Video endoscope for quality assurance of decontamination of narrow-lumened instruments

This paper presents a video endoscopic setup for inspection of narrow-lumened instruments, explaining how it can be used in hospital sterilization departments.


Recommendations by the Quality Task Group: Cooperation with the operating room and other departments

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