Blood and Plasma:
Two ways of saving life
Whole blood consists of two main components; red blood cells which represent about 45% of the volume of a unit of blood, and plasma, which is the liquid portion of blood, making up the remaining 55%. Whole blood collected from a donor can be separated into these two components by centrifugation. Plasma can be directly collected from a person by a procedure called “plasmapheresis” in which whole blood is drawn from a donor’s vein into a machine which separates plasma from the red cells by filtration or centrifugation. Once the red cells are separated from the plasma, they are returned to the donor using the same vein or a different one, depending on the machine used. The human body regenerates plasma within a few days, unlike red blood cells, which need a few weeks. For this reason, a donor can donate plasma more frequently – up to twice a week in the United States – than whole blood.
Red cells and whole blood are used to treat traumatic or surgical blood loss, as well as anemia. Plasma is used in several indications, in particular deficiencies of certain coagulation factors, as well as trauma, shock and many other medical conditions. Plasma serves also as the raw material to manufacture a number of “plasma-derived” drugs through an industrial process called “fractionation” which isolates each “fraction” of the plasma by means of various chemical and physical methods and turns them into life-saving drugs: coagulation factor concentrates, immunoglobulins, albumin and others.
The following document comprises five sections: