Blood Fractions Guide - Background

BACKGROUND. In the early days of blood transfusion, all transfusions were of whole blood. Fresh whole blood was given to patients who had either lost a significant quantity of their own blood or who had become anemic for one reason or another. Thus, those early transfusions of blood were primarily given to replace lost volume, or to restore the patient's hemoglobin level to normal values and thereby correct tissue hypoxia. It was also felt that the presence of platelets and clotting factors in the transfused blood would help to arrest any bleeding.

With the advent of blood banking however, medical science realized that by separating certain components from blood and only administering the ones specifically needed, the donated blood would go further and wastage could be reduced.

From then on, when a patient was anemic or it was felt that the oxygen-carrying capacity of his blood needed enhancing, he would only be given red blood cells.

A patient suffering hypovolemia or shock might be given plasma to restore normal blood volume, or for its albumin content, or because the clotting factors could address a bleeding disorder.

Platelets might be administered to a patient with ongoing bleeding, and white blood cells might be given to a patient whose immune system was struggling to combat an infection. Red cells, white cells and platelets are often given to patients whose bone marrow function has become impaired due to chronic illness, or as a result of chemo- or radiotherapy.

The red cells, white cells and platelets are referred to by hematologists as the formed elements.

Because the formed elements and the plasma are the major constituents of blood, were the first components to be separated from whole blood, and because they play such a fundamental role in the immediate life support and maintenance of the body, many have termed them the "primary components" of blood. The process of separating blood into its various medically useful components is known as pheresis.

In the course of time the four primary components were further processed so as to yield a number of other products, sometimes referred to as "minor blood fractions�" ...

Full article can be found on the NoBlood Wiki http://wiki.noblood.org/FractionsBackground