Apheresis

from Wikipedia, the free encyclopedia

Therapeutic apheresis

In the therapeutic apheresis (of gr. Ἀφαιρέω "take away"), commonly known as hemodialysis or blood purification process called, is a method for extracorporeal, outside of the body takes place, removal of pathogenic (disease-causing) or surplus components (proteins, protein-bound Substances and cells) from the patient's blood or blood plasma . After the pathogenic substances have been removed, the “cleaned” blood is returned.

Therapeutic apheresis is a recognized therapeutic procedure and methodologically comprises different techniques:

  1. Unselective plasmapheresis , in which the plasma is separated from the blood and completely substituted. Human blood products such as albumin solution or fresh frozen plasma ("Fresh Frozen Plasma", FFP) are mostly used as replacement fluids . This process is also known as plasma exchange.
  2. Selective plasmapheresis (also: plasma perfusion), in which the pathogenic substances or proteins are separated from the plasma by filtration or adsorption and the purified plasma is then returned to the patient, for example lipid apheresis , immunoadsorption or rheopheresis .
  3. Whole blood apheresis (also: hemoperfusion), in which pathogenic substances are filtered directly from the blood. Here, too, there are applications in the form of lipid apheresis or immune adsorption . Furthermore, the reduction of erythrocytes in the case of iron excess z. B. Hemochromatosis .

Apheresis for obtaining blood components

The apheresis can also be used as a method to gain from a healthy human blood components used as a donor substances. In contrast to whole blood donation , this procedure enables individual blood components to be obtained in high purity and yield. Apheresis methods are used to collect thrombocytes (blood platelets), blood plasma, erythrocytes (red blood cells) or peripheral blood stem cells (see stem cell apheresis ).

Only with the help of apheresis processes is it possible to obtain sufficient amounts of blood components from individual donors that only make up a small proportion of the blood (e.g. platelets, blood stem cells). Modern treatment methods for cancer, such as the transplantation of blood stem cell preparations and the subsequent necessary substitution with high-dose platelet preparations, have only been opened up by apheresis technology.

In the apheresis procedure, the donor's blood is taken from the arm vein and fed into a closed, sterile and single-use tube system (apheresis set). There it is mixed with a small amount of anticoagulant solution that contains citric acid ( sodium citrate ), which prevents the blood from clotting in the apheresis system.

The blood / anticoagulant mixture is fed into a centrifuge, in whose artificial gravity field the blood components separate into layers according to their density. Those blood components that are to be obtained can now be collected. Often only preparations of one blood component are obtained during apheresis, but in recent years efficient multi-component methods have also been developed in which several blood components can be collected in parallel. All blood components that are not required are returned to the blood donor. There the anticoagulant is broken down immediately by the liver so that the donor's blood clotting remains unaffected.

Cell apheresis device

Depending on the type of blood components to be collected, the constitution of the donor and the apheresis system used, the duration of apheresis procedures is very different:

  • 30-75 minutes to collect plasma
  • 20-30 minutes to collect red blood cells
  • 40-90 minutes to collect platelets
  • 90–240 minutes to collect blood stem cells

Apheresis procedures are not very stressful for blood donors. Side effects can include a. Reactions to the anticoagulant (e.g. metallic taste, citrus taste, tingling of the lips, mouth and extremities) and in rare cases nausea.

Cell apheresis is also used to treat various blood diseases. In the rare disease polycythemia vera , too many erythrocytes (red blood cells) form, which can be brought to a normal level by means of blood washing.

Another area of ​​application of apheresis is the extraction of antibodies from the serum for the treatment of z. B. Viral diseases in patients who have not yet formed antibodies.

literature

  • Rolf Bambauer, Reinhard Latza, M. Rigdon Lentz (2008): Therapeutic Plasma Exchange and Selective Plasma Separation Methods - Fundamental Technologies, Pathology and Clinical Results. Pabst, Lengerich / Berlin, 3rd edition, 2009, ISBN 978-3-89967-458-3

Web links

Individual evidence

  1. ↑ A. Casian, D. Jayne: Plasma exchange in the treatment of Wegener's granulomatosis, microscopic polyangiitis, Churg-Strauss syndrome and renal limited vasculitis . In: Curr Opin Rheumatol . 23, 2011, pp. 319-330. PMID 21124082 .