Plasmapheresis (from the Greek πλάσμα—plasma, something molded, and ἀφαίρεσις—aphairesis, taking away) is the removal, treatment, and return of (components of) blood plasma from blood circulation. It is thus an extracorporeal therapy (a medical procedure performed outside the body). The method is also used during plasma donation: blood is removed from the body, blood cells and plasma are separated, the blood cells are returned while the plasma is collected and frozen to preserve it for eventual use in the manufacture of a variety of medications.[1] The procedure is used to treat a variety of disorders, including those of the immune system, such as Goodpastures syndrome,[2] myasthenia gravis,[3][4] Guillain-Barré syndrome, lupus, and thrombotic thrombocytopenic purpura.Michael Rubinstein was the first person to use plasmapheresis to treat an immune-related disorder when he saved the life of an adolescent boy with thrombotic thrombocytopenic purpura (TTP) at the old Cedars of Lebanon Hospital in Los Angeles in 1959.[5] The modern plasmapheresis process itself originated in the [U.S.] National Cancer Institute between 1963 and 1968, [where] investigators drew upon an old dairy creamer separation technology first used in 1878 and refined by Edwin Cohns centrifuge marketed in 1953.[5]During plasmapheresis, blood (which consists of blood cells and a clear liquid called 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. Typically, a 300 ml batch of blood is removed at a time and centrifuged to separate plasma from blood cells. Continuous flow centrifugation: Two venous lines are used. This method requires slightly less blood volume out of the body at any one time, as it is able to continuously spin out plasma. Plasma filtration: Two venous lines are used. The plasma is filtered using standard hemodialysis equipment. This continuous process requires that less than 100 ml of blood be outside the body at one time. After plasma separation, the blood cells are returned to the person undergoing treatment, while the plasma, which contains the antibodies, is first treated and then returned to the patient in traditional plasmapheresis. (In plasma exchange, 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). Rarely, other replacement fluids, such as hydroxyethyl starch, may be used in individuals who object to blood transfusion but these are rarely used due to severe side-effects. Medication to keep the blood from clotting (an anticoagulant) is given to the patient during the procedure. Plasmapheresis is used as a therapy in particular diseases. It is an uncommon treatment in the United States, but it is more common in Europe and particularly Japan.[6] An important use of plasmapheresis is in the therapy of autoimmune disorders, where the rapid removal of disease-causing autoantibodies from the circulation is required in addition to other medical therapy. It is important to note that plasma exchange therapy in and of itself is useful to temper the disease process, while simultaneous medical and immunosuppressive therapy is required for long-term management. Plasma exchange offers the quickest short-term answer to removing harmful autoantibodies; however, the production of autoantibodies by the immune system must also be suppressed, usually by the use of medications such as prednisone, cyclophosphamide, cyclosporine, mycophenolate mofetil, rituximab, or a mixture of these. Other uses are the removal of blood proteins where these are overly abundant and cause hyperviscosity syndrome. Examples of diseases that can be treated with plasmapheresis: Idiopathic pulmonary fibrosis Guillain-Barré syndrome Miller Fisher syndrome[7] Chronic inflammatory demyelinating polyneuropathy Goodpastures syndrome Hyperviscosity syndromes: Cryoglobulinemia Paraproteinemia Waldenström macroglobulinemia Myasthenia gravis Thrombotic thrombocytopenic purpura (TTP)/hemolytic uremic syndrome Wegeners granulomatosis Lambert-Eaton Syndrome Antiphospholipid Antibody Syndrome (APS or APLS) Microscopic polyangiitis Recurrent focal and segmental glomerulosclerosis in the transplanted kidney HELLP syndrome PANDAS syndrome Refsum disease Behcet syndrome HIV-related neuropathy [8] Graves disease in infants and neonates Pemphigus vulgaris Neuromyelitis optica Multiple sclerosis Rhabdomyolysis Toxic Epidermal Necrolysis (TEN) Complications of plasmapheresis therapy Though plasmapheresis is helpful in certain medical conditions, like any other therapy, there are potential risks and complications. Insertion of a rather large intravenous catheter can lead to bleeding, lung puncture (depending on the site of catheter insertion), and, if the catheter is left in too long, it can get infected. Aside from placing the catheter, the procedure itself has complications. When patient blood is outside of the body passing through the plasmapheresis machine, the blood has a tendency to clot. To reduce this tendency, in one common protocol,[which?] citrate is infused while the blood is running through the circuit. Citrate binds to calcium in the blood, calcium being essential for blood to clot. Citrate is very effective in preventing blood from clotting; however, its use can lead to life-threateningly low calcium levels. This can be detected using the Chvosteks sign or Trousseaus sign. To prevent this complication, calcium is infused intravenously while the patient is undergoing the plasmapheresis; in addition, calcium supplementation by mouth may also be given. Other complications include: Hypotension Potential exposure to blood products, with risk of transfusion reactions or transfusion transmitted diseases Suppression of the patients immune system Bleeding or hematoma from needle placement
Posted on: Sun, 30 Nov 2014 06:12:55 +0000
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