Dense CO2: An Innovative Method for Sterilization of Venous Catheters at Low Temperature

Venous catheters are important medical devices which are more and more employed in medical treatment. After use, they are currently not re-used, a practice which is very expensive due to their cost. For this reason it is very interesting to be able to set up a sterilizing technology that permit to re-use them without changing their physical properties and the microbial adhesion. The methods usually employed for sterilization are steam (autoclave) and pure ethylene oxide (at low temperature). The aim of this work is to study the effects of different sterilization methods on catheters artificially contaminated with bacteria and yeast. Four processes were investigated: steam, ethylene oxide (Et.Ox), supercritical carbon dioxide (sc-CO2) and supercritical nitrogen protoxide (sc-N2O). The results obtained demonstrate that the supercritical fluid sterilization method provides an effective inactivation of all the microorganism tested, and that no significant modification was found in the microbial adhesion capacity to the catheter surface when 10 subsequent treatments were performed on the same sample. Inactivation kinetic for sterilization by sc-CO2 and sc-N2O were carried out at 40°C and 100 bar. The best results were obtained with sc-CO2, which allowed a faster treatment.