Chapter 91: Red Cell Transfusion

STORAGE AND PRESERVATION OF BLOOD

• Erythrocytes are preserved by liquid storage at 4°C or by frozen storage at either –80°C or –150°C.

• Preservative solutions for liquid storage all contain glucose, to provide energy, and citrate buffer at an acid pH to prevent coagulation by binding calcium and to counter the marked rise in pH that occurs when blood is cooled to 4°C.

• CPD-adenine is the preservative solution most frequently used in the United States at present. It contains adenine, citrate, phosphate, and dextrose (glucose).

• Adenine is added to help maintain intracellular levels of ATP.

• Erythrocytes are then separated and stored in an additive solution that contains glucose, adenine, and mannitol.

• The remainder of the blood collection is separated into plasma and platelets.

• Stored erythrocytes develop the so-called storage lesion, characterized in part by reduced levels of ATP, which interfere with glucose metabolism and reduce cell viability. 2,3-Bisphosphoglycerate levels also rapidly fall during storage, which increase the oxygen affinity of hemoglobin and thereby decreases the initial effectiveness of reinfused red cells. Potassium also leaks rapidly from stored cells.

• Frozen storage requires a cryoprotective agent to avoid hemolysis during freezing and thawing. Glycerol is the most frequently used agent. With proper technique, more than 80% of erythrocytes will survive frozen storage and function normally after transfusion.

WHOLE-BLOOD PREPARATIONS

• A unit of whole blood contains 435 to 500 mL of blood and 14 to 15 mL of preservative-anticoagulant solution for each 100 mL. Thus, if 450 mL of blood is collected, stored, and transfused, the patient will receive about 515 mL of total fluid.

• Blood collected in CDPA-1 (CDP with adenine) may be used after storage up to 35 days.

• There are very few, if any, indications for whole blood, and it is rarely used in modern transfusion practice.

FRESH BLOOD

• When blood is stored, platelet viability is lost within 48 hours, and the activity of coagulation factors V, VIII, and IX falls significantly.

• Thrombocytopenia and deficiency of the labile coagulation factors may occur in patients who receive transfusions of banked blood equal to their total blood volume in 24 hours.

• Fresh blood is often requested in an effort to avoid administration of blood deficient in these hemostatic components.

• It is better to treat such patients with a combination of packed red cells, fresh-frozen plasma, and platelet concentrates.

• Whole blood or packed red blood cells less than 5 to 7 days old should be transfused to patients with severe renal or hepatic disease or to newborns receiving exchange transfusion in order to avoid infusing excess free potassium.

• Patients who require massive transfusion should be given at least part of the transfusion as blood less than a few days old in order to avoid oxygen release problems caused by depletion of red cell 2,3-bisphosphoglycerate and to prevent replacement with platelet-poor blood.

• Patients with chronic transfusion-dependent anemia should probably receive blood less than 10 ...