Blood samples Within the kind of surgical procedures chosen for this study the chance of red cell transfusion is about 60 - 70%. In terms of figures 10 non-transfused cases could be gained within 40 cases in total. However, transfusion or non-transfusion does not happen in a row. We expect the total number of patients with blood withdrawal to be between 50 and 60. Additionally withdrawn samples currently not used for analysis will stored for further studies.