Plasmapheresis
The term plasmapheresis ( plasma separation) describes
- the process of blood plasma separation, specifically the extraction of the plasma during donation manually (out of date) or automatically with plasmapheresis devices (preparative plasmapheresis) or
- the exchange of blood plasma as a therapeutic measure.
Preparative plasmapheresis
Blood flows through a needle in the congested vein of the crook of the arm in a process controlled by pumps, pressure and optical sensors. In the narrow-cylindrical centrifuge, plasma that is as pure as possible is separated, collected in a transparent foil bag and weighed. This fraction is yellow, more transparent in a layer thickness of 5 cm, clouding caused by fat droplets is undesirable and interferes with the filtration. The blood cell-rich fraction is dark red and opaque from a layer thickness of 1–2 mm, and significantly thicker than the venous blood and is collected in a return container with an approximately 200 ml capacity and diluted with isotonic saline solution and fed back in cycles. Once the target amount of plasma has been reached and the last portion of thick blood has flowed back, the set including the centrifuge is rinsed with saline solution in order to return the blood cells as completely as possible.
This separation process is a special form of apheresis . The plasma collection bag is hermetically sealed by welding the inlet hose and frozen quickly, at the latest within an hour. This product can be processed into plasma for direct therapeutic application or is used as a raw material for fractionation and for plasma derivatives in industry.
The donation process takes around 30 to 70 minutes for a donor. The advantage of pure plasma donation compared to a whole blood donation with subsequent separation is that the donor only loses a few of the important red blood cells. The resulting loss of fluid is quickly compensated for by the inflowing cell water from the tissue, so that the donor is hardly stressed. In contrast to blood cells , the proteins in the plasma, such as coagulation factors and albumin, are fully balanced and replaced within two days to a week, which means that the donor is able to donate again very quickly. In the case of a whole blood donation, at least eight weeks (56 days) recovery would be necessary before the next donation.
The frozen blood plasma is processed further and made into fresh plasma concentrates (FFP, GFP), which are used as frozen or lyophilized preparations for the treatment of coagulation disorders, plasma exchange and massive transfusion. However, it is mainly used by plasma fractionation for the production of human albumin solutions, coagulation factors and immunoglobulins (plasma derivatives).
Therapeutic plasmapheresis
Therapeutic plasmapheresis is an exchange treatment in which the patient's own plasma is centrifuged and filtered using a plasmapheresis device, but at the same time is replaced by a substitution solution that contains electrolytes, buffer substances (usually hydrogen carbonate) and around five percent albumin or fresh plasma concentrates. This recipe simulates the body's own plasma.
This form of treatment, which is usually carried out by nephrologists , is used for autoimmune diseases that require the rapid elimination of antibodies or antigen-antibody complexes from the blood, since otherwise severe organ damage or death are unavoidable, for life-threatening poisoning, in which the toxin shows a high protein binding, as well as in a pathological increase in plasma proteins with a subsequent increase in viscosity with the appearance of central nervous symptoms. In the first years after the creation of the technical possibilities for therapeutic plasmapheresis, the indications were broad, but nowadays the demonstrably meaningful areas of application are very limited with increasing experience: Goodpasture syndrome and the hyperviscosity syndrome occurring in the context of plasmacytoma diseases are treated with plasmapheresis, the use in Sudden hearing loss is currently (2006) under discussion. Furthermore, plasmapheresis plays an important role in the therapy of relapsing multiple sclerosis if treatment with glucocorticoids fails. The use of plasmapheresis is also established in Guillain-Barré syndrome , thrombotic-thrombocytopenic purpura and in chronic inflammatory demyelinating polyneuropathy (CIDP) .
Individual evidence
- ↑ Weinshenker et al .: A randomized trial of plasma exchange in acute central nervous system inflammatory demyelinating disease. Ann Neurol. 1999 Dec; 46 (6): 878-86, PMID 10589540 .
