[Reduction of bacterial contamination during mechanical autotransfusion by uv irradiation--initial results].
To investigate the effects of UV-radiation of autologous blood on bacteria and red blood cells when using intraoperative sampling of autologous blood using a cell separator--an established method for reducing the need for donor blood during surgery--which is reported to have a bacterial contamination rate of 5-75%, due mainly to coagulase-negative staphylococci (CNS). Cell-separator blood was diluted to a haematocrit level permitting transmission of 1% of the UV-radiation used in this study (lambda 254 nm, coat thickness 1 mm). CNS samples were irradiated for 2, 4, 10, 20 and 30 seconds. Free haemoglobin and methaemoglobin levels were measured, and erythrocytes examined microscopically at the end of the procedure. Blood samples had to be diluted to a haematocrit of 1% to permit transmission of 1% of the UV light. The optimal irradiation duration was 4 seconds, when bacteria were completely eliminated. Longer irradiation durations were associated with increasing levels of free haemoglobin and methaemoglobin, the levels of which at 4 seconds exposure were 12.5 mg/L and 15.5%, respectively. It is possible to prevent CNS contamination of cell-separator blood by irradiation with UV light. Prior to clinical application, however, the method will need to be modified to minimize side effects and increase its decontamination efficacy.