Plasmapheresis (from the Greek πλάσμα, plasma, something molded, and ἀφαίρεσις aphairesis, taking away) is the removal, treatment, and return or exchange of blood plasma or components thereof from and to the blood circulation. It is thus an extracorporeal therapy, a medical procedure performed outside the body.
Three general types of plasmapheresis can be distinguished:
Autologuous, removing blood plasma, treating it in some way, and returning it to the same person, as a therapy.
Exchange, a patient's blood plasma is removed, while blood products are given in replacement. This type is called plasma exchange (PE, PLEX, or PEX) or plasma exchange therapy (PET). The removed plasma is discarded and the patient receives replacement donor plasma, albumin, or a combination of albumin and saline (usually 70% albumin and 30% saline).
Donation, removing blood plasma, separating its components, and returning some of them to the same person, while holding out others to become blood products that this person donates for those in need. In such a plasma donation procedure, blood is removed from the body, blood cells and plasma are separated, and the blood cells are returned, while the plasma is collected and frozen to preserve it for eventual use as fresh frozen plasma or as an ingredient in the manufacture of blood products.
Plasmapheresis of the autologous and exchange types is used to treat a variety of disorders, including those of the immune system, such as Goodpasture's syndrome, Guillain–Barré syndrome, lupus, myasthenia gravis, and thrombotic thrombocytopenic purpura.
During plasmapheresis, blood, which consists of blood cells and a clear liquid called blood plasma, is initially taken out of the body through a needle or previously implanted catheter. Plasma is then removed from the blood by a cell separator. Three procedures are commonly used to separate the plasma from the blood cells, with each method having its own advantages and disadvantages:
Discontinuous flow centrifugation: One venous catheter line is required.