The purpose of the transfusion of packed red blood cell is to overcome acute or chronic anemia cause tissue hypoxia. It increases hemoglobin concentration and consequently increase oxygen delivery to peripheral tissues. The perioperative period of major surgery is a field particularly favorable to the development of tissue hypoxia, which is associated with increased mortality and postoperative morbidity. Optimization of oxygen transport to tissues at the preoperative period is accompanied by a significant reduction of these major complications.