Plasma based technologies for reprocessing of medical devices, endoscopes and catheters

Medical endoscopes are most complex and expensive devices for intracorporeal diagnostic and surgery. A treatment with such a device always includes the risk of endoscopic associated nosocomial infections. A consequent infection prophylaxis mainly includes safe cleaning and sterilization methods for the endoscopes. Conventional used chemical gases are mostly toxic as well as carcinogenic and therefore special safety conditions have to be fulfilled. Furthermore, those agents lead to material damage and biocompatibility difficulties. Cold atmospheric pressure plasmas have a huge potential for the sterilization of such complex medical devices and therefore are of great scientific and hygienic interest. Two possible applications of non-thermal atmospheric plasma for the decontamination of medical devices, especially ones with long fine-lumen tubes, were realized. The first uses the plasma directly and is based on a bifilar helix electrode configuration in a long flexible PTFE tube. The bifilar helix electrode tube was integrated in a demonstrator, which is able to simulate the realistic steps of endoscope reprocessing. These steps include rinsing and drying. Afterwards, a plasma step was added. The tubes (1 m) were contaminated with 10⁶ cfu . tube^-1 endospores of Bacillus atrophaeus. A total reduction of ≥4 log steps was achieved. The second uses the plasma indirectly and is based on a microwave driven discharge processed gas. The antimicrobial efficacy of the plasma processed gas against bacterial spores of B. atrophaeus was investigated. The gained results showed inactivation rates up to 4 log cfu . tube^-1 for a 10 seconds plasma pulse, only. The total process time was up to 30 minutes. The developed microwave driven discharge was integrated in a commercial available formaldehyde sterilizer. Medical devices and any imaginable good, shape independent, can be decontaminated. Both developed and investigated plasma technologies hav- high microbial inactivation efficiency and are characterized by advantages like no thermal influence, less toxicity for human and environment and low costs.