Red blood cell hemolysis during processing

Red blood cell (RBC) hemolysis has been reported in units of RBC for transfusion. This has significant clinical implications for transfused patients because the free hemoglobin dissociates into dimers that have to be bound to haptoglobin to be removed by the reticuloendothelial system. Once the binding capacity of haptoglobin has been exceeded, hemoglobinemia occurs. Hemolysis is caused by the breakdown of the RBC, causing release of hemoglobin and resulting in the discoloration of the plasma. Abnormal hemolysis in an individual RBC unit may be caused by several factors including inappropriate handling during processing of blood, inappropriate storage conditions, bacterial hemolysins, antibodies that cause complement lysis, defects in the RBC membrane, or an abnormality in the blood donor. The degree of hemolysis is described as the percent of free hemoglobin in relation to the total hemoglobin with appropriate correction for the hematocrit. The acceptable level of hemolysis has not been established in North America, but the value of 1% currently is used to assess biocompatibility of blood storage materials, whereas the Council of Europe has set the standard at 0.8%. This report emphasizes the need for the adequate control of the various processes that are involved in the preparation of RBCs from whole blood to minimize the occurrence of hemolysis. Careful evaluation of manufacturing processes will minimize RBC wastage caused by hemolysis. Copyright (C) 2002 by W.B. Saunders Company.