SvO2 Trigger in Transfusion Strategy After Cardiac Surgery

Currently, the rate of transfusion of cardiac surgery patients is approximately 50%. The decision to transfuse is based on the hemoglobin (Hb), the transfusion threshold from 7 to 9 g / dL seems to be reasonable, based on clinical parameters, as well as patient history, as the degree of coronary stenosis . Several randomized studies have shown that a restrictive transfusion strategy was superior to a liberal strategy. ScvO2 is a parameter reflecting the balance between transport O2 and O2 in tissue consumption, which Hb is one of the determinants. It requires that a levy on central venous used frequently for such patients. ScvO2 could make better account of the actual tolerance of anemia that the only value of Hb and the patient's clinical characteristics. We therefore hypothesize that ScvO2 can help with the decision of RBC transfusions after heart surgery. Primary and secondary endpoints Principal: To assess the value of ScvO2 threshold (65%) in the restrictive transfusion strategy on the incidence of transfusion after cardiac surgery. secondary: * Assess the impact of transfusion strategy based on ScvO2 on the number of transfused patients at D28 * Assess the impact of transfusion strategy based on ScvO2 on the number of cells transfused concentrates. * Assess the impact of transfusion strategy based on ScvO2 on mortality or incidence of disease events such as cardiac complications, renal, respiratory or neurological dysfunction in the immediate aftermath of surgery.