By Dr Tomislav Meštrović, MD, PhD
Plasma donation is a process where plasma is separated and collected from the whole blood, while the unselected constituents of the blood are returned to the donor. Blood is composed of four major components: red blood cells, white blood cells, platelets and plasma. Plasma is a liquid portion of the blood that transports clotting factors, proteins and other nutrients throughout the bloodstream.
Plasma donation is sometimes also called plasmapheresis, but a distinction from therapeutic plasmapheresis has to be made. For treatment applications the goal of plasmapheresis is to deplete the circulating substances directly responsible for the disease process. On the other hand, the aim of collecting plasma for transfusion is an efficient removal of the specific blood elements, without causing harm to the donor due to the over-depletion.
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Methods of collecting plasma
In the early days, manual plasmapheresis was the principal method of collection. The blood was drawn into a primary pack containing anticoagulant and a series of additional packs. It was then centrifuged, while simultaneously maintaining the intravenous line with a saline drip. The plasma was extracted and retained, and the red blood cells were returned to the donor. The whole procedure was repeated (so called “double plasmapheresis”), yielding a total of 500 ml of plasma in one hour time.
Although manual method of collection is still available, automated equipment is now used routinely due to its convenience and improved product safety. The advantages of automated plasmapheresis is that the procedure is faster and more tolerable, donors are never disconnected from their own blood (hence no risk of contamination), and the total extracorporeal volume is less than in double plasmapheresis.
Several machines have been constructed exclusively for this purpose. They are based either on the principle of centrifugation as a way to separate the blood components or filtration through a spinning cylindrical membrane. In modern instruments the dose of anticoagulant is also measured in an automated way, controlled by a microprocessor.
Products made from plasma
Different products can be made from plasma donations. Immunoglobulins are preparations containing antibodies used to protect patients from several infectious diseases such as varicella zoster, hepatitis B and tetanus. Intravenous immunoglobulins are also used to boost the immune system in people with various immune deficiencies, and in the treatment of a growing number of hematologic, immunologic and neurologic illnesses.
Albumin from plasma is used to restore blood volume in shock or burns patients, as well as to assist in the treatment of kidney and liver diseases. Concentrate of factor VIII (anti-hemophilic factor) is used to prevent bleeding in patients with hemophilia A and von Willebrand disease (VWD) – a well-known hereditary coagulation abnormalities caused by a deficiency in factor VIII and von Willebrand factor, respectively.
Care of donors
The criteria for the acceptance of plasma donors are stricter than for routine blood donation. Annual examination of donors is often mandatory, and comprehensive laboratory tests are carried out periodically. Detailed informed consent should be signed before the start of the procedure, and every donor should be aware of all possible hazards.
If plasma donors do not have their red blood cells returned during the procedure, or give whole blood, at least 8 weeks should elapse before the next donation. Regulations in the USE and Europe differ significantly; the maximum amount of plasma that can be donated in the USA is 50-60 liters a year, but in Europe it is only 15 liters per year.
Outbreaks of blood-borne diseases in donation centers have been described. These outbreaks arose because of practices associated with human blood injection, reuse of material, and sharing of syringes or intravenous lines during apheresis. Thus commercial plasma donation in less-developed countries puts donors and recipients at risk of contamination of the plasma pool by blood-borne pathogens.
- Klein HG, Anstee DJ. Exchange transfusion and haemapheresis. Mollison's Blood Transfusion in Clinical Medicine. 11th edition, Blackwell Publishing Ltd, 2005; pp. 774-782.
- Harris SB, Hillyer CD. Blood banking and blood manufacturing. In: Hilleyr CD, ed. Blood Banking and Transfusion Medicine: Basic Principles & Practice. 2nd edition, Chruchill Livingstone Elsevier, 2007; pp. 183-204.
Last Updated: Sep 10, 2014