Plasma exchange

Plasmapheresis refers to the removal, treatment, and return of blood plasma from blood circulation.

Utilizes an extracorporeal therapy.

This process can also be used to collect plasma for further manufacturing into a variety of medications.

Used to treat a variety of disorders, including those of the immune system, such as Myasthenia gravis Guillain-Barré syndrome, lupus, and thrombotic thrombocytopenic purpura.

During plasmapheresis, plasma is removed from the blood by a cell separator.

Therapeutic plasma exchange involves removal of large volumes of plasma, albumin or both.

The purpose of therapeutic plasma exchanges to remove pathological solutes, such as autoantibodies, immune complexes, cryoglobulins, myeloma light chains or cytokines.

Three procedures are commonly used to separate the plasma from the blood cells: Discontinuous flow centrifugation, continuous flow centrifugation and plasma filtration.

Discontinuous flow centrifugation utilizes one venous catheter line and about 300 ml batch of blood is removed at a time and centrifuged to separate plasma from blood cells.

Continuous flow centrifugation utilizes two venous lines and requires slightly less blood volume to be out of the body compared to the discontinuous flow centrifugation at any one time as it is able to continuously spin out plasma.

Plasma filtration also uses two venous lines and the plasma is filtered using standard hemodialysis equipment and this continuous process requires less than 100 ml of blood to be outside the body at one time.

Following plasma separation, the blood cells are returned to the person undergoing treatment.

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.

Albumin is the most common fluid for replacement for therapeutic plasma exchange (TPE).

Normal plasma’s oncotic pressure is the same as 5% albumin, therefore replacing plasma with 5% serum albumin maintains plasma volume and blood pressure.

Utilizing albumin does not replace coagulation factors, and post treatment coagulopathy may occur.

Plasma as a replacement fluid avoids post procedure coagulopathy and immunoglobulin deficiency, but may be associated with transfusion reactions, citrate toxicity and has potential for viral transmission.

Plasma replacement fluid with TPE is indicated to replace ADAMSTS13 when treating thrombotic thrombocytopenic purpura or when a coagulopathy must be corrected.

Other replacement fluids, such as hydroxyethyl starch, may be used in individuals who object to the use of blood products.

Plasmapheresis utilized as therapy for autoimmune disorders, where the rapid removal of disease-causing autoantibodies from the circulation is required.

Provides the most rapid technique for the removal of harmful autoantibodie.

The process may also decrease the production of autoantibodies by the immune system, usually by the use of medications such as prednisone, cyclophosphamide, cyclosporine, mycophenolate mofetil, rituximab or a mixture of these.

Other uses include the removal of blood proteins that cause hyperviscosity syndrome.

Therapeutic plasma exchange may have immunomodulatory effects, including modulation of Th1/Th2 T cell balance toward Th2, suppression of interleukin-2 and interferon gamma production,, and increase in suppressor T-cell function.

Diseases that can be treated with plasmapheresis include: Antiphospholipid Antibody Syndrome, Behcet syndrome, Chronic inflammatory demyelinating polyneuropathy, Cryoglobulinemia, Guillain-Barré syndrome, Goodpasture’s syndrome, Graves’ disease in children, HIV related neuropathy, HELLP syndrome, Hyperviscosity syndromes of Paraproteinemia, and Waldenström macroglobulinemia, Lambert-Eaton Syndrome, Microscopic polyangiitis, Multiplevsclerosis, Myasthenia gravis, Pemphigus vulgaris, Refsum disease, recurrent focal and segmental glomerulosclerosis, in transplanted kidneys, Rhabdomyolysis, Thrombotic thrombocytopenic purpura (TTP)/hemolytic uremic syndrome, Wegener’s granulomatosis

Complications of plasmapheresis therapy: catheter complications, thromboembolism, citrate anticoagulant induced hypocalcemia, exposure to blood and blood products, hemorrhage, hypotension, hypoxia, serum sickness and immunosuppression.

Treatment of choice for TTP/HUS.

Plasmapheresis can effectively decrease IgM levels that are elevated and symptomatic in patients with Waldenstrom’s Macroglobulinemia.

Has been a mainstay of induction therapy for patients with antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis who have rapidly progressive glomerulonephritis or diffuse alveolar hemorrhage.

Plasma exchange rapidly depletes pathogenic ANCA’s and should theoretically diminish vascular injury and organ damage and hasten resolution of the disease.

Relatively small reductions of 20-30% of plasma proteins can reduce serum viscosity by as much as 50-60%.

Plasmapheresis in the US is performed by automated methods such as the Plasma Collection System (PCS2) made by Haemonetics or the Autopheresis-C (Auto-C) made by Fenwal.

Manual method of plasmapheresis involves the collection of whole blood, which is separated by centrifuge machines, and the plasma is pressed out of the collection set to a satellite container.

The red blood cells are returned to the donor.

A donor can provide up to a liter of plasma at a time and can donate with only a few days between donations.

Manual collection procedures have been essentially replaced by automated methods.

The automated method collects, separates, and returns the blood via a machine which is connected to the donor through a needle placed in the arm, typically the antecubital vein.

The removed plasma may be replaced by saline.

The body will typically replace the collected volume within 24 hours.

Standard therapeutic plasma exchange procedure exchange is 1-1-1/2 plasma volumes resulting in the removal of 60-70% of intravascular large molecular weight solutes.

Some large molecules such as immunoglobulin IgG may be distributed into both the intravascular and extravascular spaces.

During therapeutic plasma exchange, extravascular molecules can move into the intravascular space.

The collected plasma is frozen at lower than -20 °C (-4 °F) and is processed for fractionation, or transfused as Fresh Frozen Plasma (FFP).

Plasma exchange removes normal plasma coagulation factors such that factor V, VII, VIII, IX and X, as well as von Willebrand’s factor may decline significantly.

Factors VIII, IX, and vWF return to normal within 4 hours after the procedure, while the other factors normalize within 24 hours except for the fibrinogen level.

The fibrinogen level reaches 2/3 of normal level within 72 hours of therapeutic plasma exchange.

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