After randomisation, patients will be eligible to receive RBC according to their level of Hb in the standard group and according to the Hb and ScvO2 in the optimization group. Patients without any disease are transfused if their Hb level is below 7g/dL; patients older than 60 years or having sepsis are transfused if their Hb level is 8g/dL or lower and cardiac patients are transfused if their Hb level is 9g/dL or lower. In the second group, transfusion is performed if and only if the ScvO2 level is les than 70% when Hb is under the same threshold levels.