Perioperative Transfusion Triggers for Red Blood Cells.

Perioperative transfusion triggers for red blood cell (RBC) transfusion include physiologic signs of inadequate oxygenation of the entire organism or a specific organ, hemoglobin (Hb) concentration and logistic aspects such as experience of anesthesiologists and surgeons, predictability and magnitude of blood loss and time required for a Hb determination and RBC delivery. At a Hb concentration <6 g/dL a RBC transfusion may be given, however, if the patient is hemodynamically stable one may opt not to transfuse. With Hb concentrations between 6 g/dL and 10 g/dL physiologic signs of inadequate oxygenation decide on RBC transfusion. In absence of hypovolemia signs of inadequate oxygenation include tachycardia and hypotension, an O2 extraction>50%, a a mixed-venous O2 partial pressure <4.3 kPa (32 mmHg), a decrease of O2 consumption >10% (not otherwise explained) and signs of locally deficient oxygenation such as myocardial ischemia. At Hb concentrations >10 g/dL, RBC transfusions are rarely, if ever, indicated.