[Perioperative transfusion]

In the past, red blood cells were given in case of acute anemia, the decision being often based on the hemoglobin concentration alone. The clinical situation and the comorbidities of the patient as well as the secondary were given only a little, if any, consideration. Presently, the evidence shows that red blood cells transfusion has to be individualized in every single patient, taking into consideration the risks of the transfusion, the coexisting medical problems and the patient's tolerance to acute anemia. Experimental and clinical research confirms that a much lower hemoglobin concentration can be tolerated than previously admitted if normovolemia is preserved, the most important transfusion trigger being a sign of insufficient oxygen consumption and signs of an inadequate circulation.