Plasmapheresis consists of taking blood from a subject, with immediate separation of the liquid component from the corpuscular component (red blood cells, white blood cells and thrombocytes); all thanks to the help of an automated mechanical separator, which divides the two components through centrifugation. During plasmapheresis, therefore, only the liquid part of the blood (plasma) is removed from the donor, while the cellular component is returned to him through the same collection needle. The cell separator, in fact, works in cycles consisting of an initial phase of blood sampling – with separation and collection of the plasma – and a subsequent phase of reinfusion of the corpuscular component.
Plasmapheresis is a fundamental procedure for the production of so-called plasma-derived drugs. In the liquid component of the blood, in fact, we find significant quantities of proteins, therefore antibodies (immunoglobulins), peptide hormones, coagulation factors and proteins necessary for the transport of insoluble substances. Respiratory gases and all the various nutrients (glucose, vitamins, amino acids, fatty acids, etc.) are also present in the plasma.
The protein component of plasma is fundamental for the production of drugs for patients with deficits in specific plasma substances; subjects affected by haemophilia A and B, for example, have a strong deficiency of coagulation factors VIII or IX, which can be extracted and purified from the donor’s plasma and then administered to the recipient.
Furthermore, “whole” plasma can be administered as is to patients suffering from particular pathologies, which require its replacement due to excess abnormal antibodies or other reasons.
Going beyond the scope of donations, there is also therapeutic plasmapheresis, aimed at the simple removal of plasma molecules present in excess (bilirubin, LDL, etc.). In these cases, the most correct term is given by the name of the isolated pathogenic molecule, followed by the term apheresis (from “afero”, to take away).
Questions and answers about plasmapheresis (plasma donation)
HOW MUCH PLASMA IS TAKEN? Normally, 500 ml of plasma is collected during plasmapheresis. The donation can be made once every three months but also once every 14 days; according to current law, it is in fact possible to make up to 20 500ml plasma donations per year.
IS PLASMAPHERESIS DANGEROUS FOR THE DONOR’S HEALTH? The plasma volume is immediately compensated through the integration of oral fluids (drinking before and after the collection), or through the infusion of physiological solutions during the restitution of the cells.
The lost protein components are instead replaced within three days (coagulation factors and fibrinogen are recovered in 24 hours, immunoglobulins in 48 and complement c3 within 72 hours).
WHAT CHARACTERISTICS MUST THE DONOR HAVE? To be eligible for plasmapheresis, the donor must weigh more than 50 kg, be aged between 18 and 55-60 years, and meet a series of requirements, such as protein levels above 6 grams/dL, number of platelets above to 200,000/mL, and hemoglobin values greater than 12.5 g/dL, if a man, or 11.5 g/dL if a woman. Although the plasma is tested for the presence of infectious diseases (viral hepatitis, AIDS, etc.), it is important that the donor does not have risky sexual intercourse. Furthermore, it is essential to declare to the doctor the intake of any medication, in order to evaluate the possibility of postponing the donation.
We remind you that the donor has the right to a day of paid rest from work (for employees) and to periodic and free medical and laboratory checks (hemoglobin, transaminase, urea nitrogen, triglyceridemia, glycemia, ferritinemia, cholesterolemia, hepatitis B and C, AIDS, and all those who are appropriate).
HOW LONG DO PLASMAPHERESIS PROCEDURES LAST? The duration of the donation increases as the hematocrit increases and the blood flow guaranteed by the collection vein decreases. On average, 40 minutes are needed, with fluctuations ranging from 30 to 60 minutes based on the aforementioned factors. During this period of time, 2 to 3 cycles are completed, consisting of two separate phases, one of which is collection, separation and accumulation, and one of reinfusion of the corpuscular component.
WHAT DOES ACD-A MEAN? It is a solution of citric acid and dextrose, used as an anticoagulant during plasmapheresis (ACD-A = Anticoagulant Citrate Dextrose Solution A). We are talking about a safe drug, which can only cause a temporary decrease in blood calcium, signaled by the appearance of tingling in the lips. If this symptom does not resolve within a few minutes, simply take a calcium tablet to make the continuation of plasmapheresis more comfortable.