Blood components are obtained from blood from volunteer blood donors. Blood donation programs allow blood to be donated by:
- A patient for themselves
- Anonymous donors
- In some cases, by someone specified by the patient
Blood may be processed into any of these blood components:
Whole blood contains red blood cells and plasma. Whole blood is often used for open heart surgery. It may also be used for exchange transfusions (complete replacement of a baby's blood) in newborns with hemolytic disease of the newborn. It is not common for this product to be used for other reasons.
Packed Red Blood Cells
Red blood cells carry oxygen to the tissues. Packed red blood cells have had most of the plasma removed from the whole blood. Packed cells are most often given into a vein over two to four hours. This is given to replace the red cells lost through bleeding, hemolysis (destruction of the red blood cells), or when the bone marrow produces fewer red cells. The decreased production of cells may be due to bone marrow failure, cancer involving the marrow, the effect of chemotherapy drugs used to treat a cancer, or anemia due to prematurity.
Fresh Frozen Plasma
Contains clotting factors. Fresh frozen plasma is plasma which was frozen and stored shortly after it was obtained from the blood donor. Fresh frozen plasma contains many clotting factors. It is often used alone or with cryoprecipitate to replace the low levels of clotting factors. It is most often given into a vein over one to two hours.
Blood cell fragments which help blood clot. Platelets are the cell fragments which prevent or stop bleeding or bruising by plugging the hole in the blood vessel. Platelets are most often given into a vein over a few minutes to an hour. If a patient's bone marrow is not making platelets, then platelet transfusions are most often needed one time or two times a week (or even more often). Platelets may also be given when a patient's platelets are not working the right way due to medicines, illness, or mechanical damage (such as from an artificial heart valve).
Cryoprecipitate is the part of the blood which contains only certain clotting factors such as factor VIII (deficient in hemophilia A), von Willebrand factor and fibrinogen. Cryoprecipitate is now most often given only as a source of fibrinogen (needed for forming a clot). Some patients with certain types of hemophilia or patients who lack fibrinogen may receive cryoprecipitate to treat their clotting defect. Also, very ill patients may develop an abnormal clotting condition known as DIC (disseminated intravascular coagulation). This can cause a decrease in the body's clotting factors and result in severe bleeding. Cryoprecipitate, along with fresh frozen plasma (see above), may be given to help replace the clotting factors that are low. Cryoprecipitate is most often given over just a few minutes to an hour into a vein.
Cells which help fight infections. Granulocytes are also called neutrophils. They are cells which help fight off bacterial or fungal infections. Granulocytes are sometimes given to help fight off severe infections in patients who have very low numbers of granulocytes in the blood and have not responded to medicine. Most often granulocytes are given daily for five days or until the patient's granulocyte count returns to a level which allows the patient to fight the infection on their own. Granulocytes are most often infused into a vein over one to two hours.