Initial transfusion needs aremet by type-specific rather than low titer O-negative blood. When the patient's problem approaches the magnitude of exchange transfusion (5 to 10 units) in less than 4 hours, platelet transfusion to treat dilutional thrombocytopenia is administered. Fresh frozen plasma is administered to provide clotting factors. When five units have been exceeded, platelet, pro-thrombin, and partial thromboplastin are measured. A blood clot is checked for clotting, retraction, and lysis. These tests screen platelet quantity and the intrinsic and extrinsic clotting system. Administered blood is warmed in a water bath or heating coil. Blood gas analysis (pH, pO2, and pCO2) is performed every five units to allow for precise administration of bicarbonate. The electrocardiogram is used to monitor potassium and calcium abnormalities. Hyperkalemia is seldom a problem. Hypocalcemia may be present transiently and is treated with calcium choride. Component therapy is the standard recommended practice. Fresh blood is recommended for the patient who has had an acute exchange transfusion and continues to require large quantities of blood. Fresh blood obviates the need for combining components and allows one transfusion unit to address itself to the multiple needs of the patient.