Plasmapheresis

 

 

Background

Plasmapheresis is a term used to refer to a broad range of procedures in which extracorporeal separation of blood components results in a filtered plasma product. The filtering of plasma from whole blood can be accomplished via centrifugation or semipermeable membranes
Centrifugation takes advantage of the different specific gravities inherent to various blood products such as red cells, white cells, platelets, and plasma
 Membrane plasma separation uses differences in particle size to filter plasma from the cellular components of blood
Traditionally, in the United States, most plasmapheresis takes place using automated centrifuge-based technology
 In certain instances, in particular in patients already undergoing hemodialysis, plasmapheresis can be carried out using semipermeable membranes to filter plasma
In therapeutic plasma exchange, using an automated centrifuge, filtered plasma is discarded and red blood cells along with replacement colloid such as donor plasma or albumin is returned to the patient.
In membrane plasma filtration, secondary membrane plasma fractionation can selectively remove undesired macromolecules, which then allows for return of the processed plasma to the patient instead of donor plasma or albumin.
 Examples of secondary membrane plasma fractionation include cascade filtration, thermofiltration, cryofiltration, and low-density lipoprotein pheresis. 

Indications

Plasmapheresis is currently used as a therapeutic modality in a wide array of conditionsGenerally, plasmapheresis is used when a substance in the plasma, such as immunoglobulin, is acutely toxic and can be efficiently removed. Myriad conditions fall under this category, including neurologic, hematologic, metabolic, dermatologic, rheumatologic, and renal diseases, as well as intoxications, that can be treated with plasmapheresis.
The Apheresis Applications Committee of the American Society for Apheresis periodically evaluates potential indications for apheresis and categorizes them from I to IV based on the available medical literature. The following are some of the indications, and their categorization, from the society’s 2010 guidelines
Category I (disorders for which apheresis is accepted as first-line therapy, either as a primary standalone treatment or in conjunction with other modes of treatment) are as follows:

• Guillain-Barre syndrome
• Myasthenia gravis
• Chronic inflammatory demyelinating polyneuropathy
• Hyperviscosity in monoclonal gammopathies
• Thrombotic thrombocytopenic purpura
• Goodpasture syndrome (unless dialysis dependent and no diffuse alveolar hemorrhage)
• Hemolytic uremic syndrome (atypical, due to autoantibody to factor H)
• Wilson disease, fulminant

Category II (disorders for which apheresis is accepted as second-line therapy, either as a standalone treatment or in conjunction with other modes of treatment) are as follows:

• Lambert-Eaton myasthenic syndrome
• Multiple sclerosis (acute central nervous system demyelination disease unresponsive to steroids)
• Red cell alloimmunization in pregnancy
• Mushroom poisoning
• Acute disseminated encephalomyelitis
• Hemolytic uremic syndrome (atypical, due to complement factor mutations)
• Autoimmune hemolytic anemia (life-threatening cold agglutinin disease)
• Systemic lupus erythematosus (severe)
• Myeloma cast nephropathy

Category III (optimum role of apheresis therapy is not established; decision-making should be individualized) are as follows:

• Post-transfusion purpura
• Autoimmune hemolytic anemia (warm autoimmune hemolytic anemia)
• Hypertriglyceridemic pancreatitis
• Thyroid storm

Category IV (disorders in which published evidence demonstrates or suggests apheresis to be ineffective or harmful; IRB approval is desirable if apheresis treatment is undertaken in these circumstances) are as follows:

• Stiff person syndrome
• Hemolytic uremic syndrome (typical diarrhea-associated)
• Systemic lupus erythematosus (nephritis)
• Immune thrombocytopenia