Current concepts of blood transfusion.

Extensive research into the physiology of red blood cells and platelets has shown that it is more advantageous to separate blood into its components than to store it as whole blood. After the red blood cells and platelets have reached the restricted period of storage in the liquid state, they can be freeze-preserved and stored for prolonged periods. Plasma can be frozen for future use or can be fractionated into the various stable components. The use of a combination of liquid-preservation and freeze-preservation methods affords a more efficient use of the limited supply of available blood.