Central Service - Issue 4/2004
The Spoken Word
- What’s New in Standardisation: Terms and Definitions
- Forum Medical Device Processing 2004: "What Is Needed, What’s Possible?"
- New Jersey Passes Law Mandating CS State Certification
- Second Symposium at Lucerne Unites Hospital Hygiene and Economic Feasibility Issues
- Correction by the Board of the German Society for Hospital Hygiene (DGKH)
S. Krüger*, T. Hofmann, B. Zühlsdorf:
Test Soils for Investigating the Cleaning Performance in Washer-Disinfectors as per prEN ISO 15883-1
(Zentr Steril 2004; 12 (4): 230-240)
The studies give an overview of the ease with which removal of the test soils differs under the influence of temperature and exposure time as well as of different alkaline detergents in laboratory tests conducted while suppressing the mechanical action. They concord with the recommendation by the Robert Koch Institute, stating that preference be given to alkaline detergents with a pH value of at least 10, to temperatures > 55 °C and contact times of 10 min for the cleaning step (6). On the other hand, the studies show how the cleaning performance can be improved in the face of tenacious test soils and associated, everyday residues on medical devices. Further in-depth studies with blood soils are planned.
R. Fleischhack*, P. Kober, T. Kühne, K. Scheel:
Overheating as a Result of Hygroscopic Condensation in Steam Sterilisation of Porous Items. A forgotten phenomenon that has many practical implications
(Zentr Steril 2004; 12 (4): 241-257)
A century ago while conducting experiments with flowing steam at 100°C, M. Rubner noticed that overheating was caused as a result of hygroscopic condensation between 40-50°C in textile goods. Already at that time it was also known that overheating detracted from the microbicidal activity of the steam. Using artificially dried swabs (the absolute moisture content being specified) in various types of packaging, we investigated the practical relevance of this phenomenon in modern steam sterilisation processes. We referred our measurement results to the theoretical temperature (saturated steam temperature) actually measured and to the most commonly occurring measured value (modal value or mode). The instances of overheating were in the range 0.7 und 5.6 K when referred to the modal value at 121°C and between 0.7 and 4.1 K at 134°C, depending of the degree of drying achieved and on the choice of packaging. The overheating detected was highest for conventional sterilisation of swabs welded into trays and lowest for sterilisation in containers. It is recommended that all textiles be conditioned for a sufficiently long period before being packed (adaptation to the relative humidity of at least 30% at 20°C room temperature), sterilised in stainless steel containers and that the swabs, which were welded in containers, be removed from the container to counter peaks of hygroscopic condensation.
K. H. Annecke:
Flow Measurement on Flexible Endoscopes to Prepare for Cleaning and Disinfection
(Zentr Steril 2004; 12 (4): 258-267)
The process of cleaning and disinfecting flexible endoscopes is influenced by various parameters that determine the result of the process in many different ways. The first section of this article will discuss these parameters; the second part is dedicated to deriving an optimized process from what we have learned about these parameters; and the third part will show how this optimized process can be implemented.
The objective of this study was to supplement or replace the current hypothesis - that pre-cleaning pursuant to the rules of the Robert Koch Institute (RKI) ensures safe and reproducible results of the subsequent cleaning and disinfection process - by a reproducible (verifiable) and validated physical process that ensures the reproducibility of the results before and after each procedure by measuring certain physical parameters. Obviously, simplified qualitative statements such as "the channel is blocked" are insufficient. Rather, a measurable quantity must be defined allowing a precise quantitative statement about the chances of the impending cleaning and disinfection process being successful.
RECOMMENDATIONS BY THE QUALITY TASK GROUP (AK »QUALITÄT«)
Loading Pattern and Its Implications for Successful Cleaning in the Washer-Disinfector