Indications of blood transfusion can be summed up as:
Platelet transfusion
These cells circulate in the body with the red and white cells and play an important role in the clotting process of the blood. Transfusion of platelets separated from several units of blood is now an important part of the treatment of platelet deficiency.
White cell transfusion
It is now established that successful transfusion of white cells can assist patients to combat infections when, as it sometimes happens in certain blood diseases, the patients' body is unable to produce its own white cells, These transfusions involve the use of specialised techniques and cell separation equipment. It is not possible to collect sufficient white cells through conventional blood donation.
Plasma and albumin
Plasma Protein Fraction (PPF) is a clear fluid containing approximately 5% albumin. This is an end-product of plasma fractionation, it is widely used for the treatment of surgical shock and burns or, in remote areas, to maintain the volume of fluid in the circulation until a patient can be removed to a hospital with full transfusion facilities, or until compatible blood can be provided. Thus, it is extremely valuable in small hospitals and to ships, which traditionally carried dried plasma (which has now been largely succeeded by PPF). A more concentrated solution of lbumin, about 20 per cent, is also available.
Fresh Frozen Plasma
Fresh Frozen Plasma (FFP) is prepared from freshly collected blood by spinning it in a centrifuge. On separation, the plasma is immediately deep frozen and stored at minus 40°C. FFP contains all the proteins required for normal clotting of blood, and is commonly used in clotting factor deficiency usually caused by liver diseases.
Cryoprecipitate
This is prepared from Fresh Frozen Plasma by allowing it to thaw under conditions so adjusted that the Factor VIll settles out as a solid substance or precipitate. This can be separated by removal of the greater part of the thawed plasma after spinning in a centrifuge, and then deep frozen in packs. Cryoprecipitate also contains fibrinogen, another protein essential for normal clotting of blood. In some conditions, this disappears temporarily from blood and bleeding ensues. Transfusion of cryoprecipitate rapidly corrects the deficiency of fibrinogen and stops the bleeding. It can stored for one year at minus 40°C.