Central Service - Issue 6/2011
- What's New in Standardisation: Standard Operation Procedures
- 12th Congress of the World Forum for Hospital Sterile Supply
- 12th Schleswig-Holstein CSSD Hygiene Forum
S. DiPiazza, M. Zeller, J. Thüring, S. Mauerhofer, U.B. Rosenberg:
The «Flow Cell» Evaluation of Cleaning Processes by Means of Filmic Real-Time Visualisation
The pivotal role of cleaning as part of the medical device reprocessing chain is today generally recognised. But to date there is no international standardised method to measure the cleaning performance of processes or of detergents. Developers, manufacturers and vendors of process chemicals must, nonetheless, be able to provide evidence of how their products can fulfil performance expectations. Hence already in the past a method was devised to describe the action of detergents used for automated reprocessing (1).
This paper describes a new method whose aim is to visualize the cleaning process as it unfolds. The system developed to that effect is constructed of a flow cell into which can be placed a process challenge device (PCD) harbouring a test soil. A glass object slide positioned at a distance of 1 mm above the PCD encloses the flow cell towards the top. This permits filming of the cleaning process with a digital HD video camera in macro mode as soon as the cleaning solution is pumped at a defined temperature and velocity through the flow cell.
Using various test soils on a carrier material, a whole series of different experiments was performed with this new method. We used the commercially available TOSI-PCDs as well as stainless steel plates and PTFE strips (Teflon) to which we applied test soils such as porcine brain homogenate, meat homogenate and bonemeal homogenate. In addition, exposed and developed black-white films served as a substrate for visualisation of the protease activity of enzymatic detergents. Using filmic real-time visualisation it was possible to show not only the speed of cleaning processes with various detergents but also characteristics such as detachment, solubilisation and swelling of a soil. In a further step, real-time films were compressed and mounted in parallel, thus permitting direct comparison of different experiments on a screen.
The flow cell method is a valuable tool for visualisation of the performance of a detergent, in particular if this performance is to be compared with that of other detergents or of a reference detergent (benchmarking).
M. Kamer, P. Reeßing, J. Staffeldt:
Properties of manual instrument disinfectants
The cleaning step is one of the most vital of all steps of the entire medical device reprocessing chain and is being ascribed increasingly more importance, especially against a background of transmissible spongiform encephalopathies . But, unlike when testing the disinfectant activity of disinfectants, there are no standards setting out which test method should be used to investigate the cleaning performance or should be invoked as a basis for declaration of cleaning activity. While aldehydes and alcohols are known to be protein-fixing substances, in the two-step study of the cleaning performance and protein fixation presented here it was noted that other disinfectant substances used for predisinfection of instruments also cause protein fixation and that disinfectants declared by the manufacturer as having cleaning activity were shown to, in fact, not be endowed with such activity. The aim of this publication is to present a method for testing the cleaning efficacy of manual detergents and of disinfectants declared as having cleaning activity as well as to investigate protein fixation.
Recommendations by the «Quality Task Group»: Medical device reprocessing logistics