Transfusion and Thromboembolic Prophylaxis

The number of units and frequency of transfusion is decided by the anesthetist together with the physician performing the transfusion during the first examination, which should take place at least 40 days prior to the operation, according to the clinical condition of the patient (age, weight, basal hemoglobin, any concomitant diseases) and the type of operation and expected perioperative blood loss (1). A subtraction of 350 ± 10% ml of blood from a patient weighing about 70 kg means a reduction of around 1 g of hemoglobin (Hb) and 3 units of hematocrit (Ht). Before major orthopedic surgery enough units should be predeposited so as to avoid the use of homologous blood in more than 90% of patients. Two units of autologous blood are generally needed for total knee and hip arthroplasty and spine fusion, and 3-4 units for partial or total knee or hip revision.