Fig. 1.
Flowchart. Patients were randomly assigned to control or Svo2 groups. In the Svo2 group, patients were supposed to receive transfusion provided their pre-transfusion central Svo2 was less than or equal to 65%. Severe bleeding was defined by a postoperative bleeding of more than 1,000 ml or those requiring a transfusion of more than 4 erythrocyte units within the first 12 postoperative hours.17 ICU, intensive care unit; Svo2, mixed venous oxygen saturation.