The filtering of plasma from whole blood can be accomplished via centrifugation or the use of semipermeable membranes.
Centrifugation takes advantage of the different specific gravities inherent to various blood products, such as red blood cells (RBCs), white blood cells (WBCs), platelets, and plasma. Membrane plasma separation uses differences in particle size to filter plasma from the cellular components of blood.
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| Plasmapheresis/Plasma Exchange/Therapeutic Apheresis |
Traditionally, in the United States, most plasmapheresis has been done with 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 RBCs along with replacement colloid (eg, donor plasma or albumin) are returned to the patient.
In membrane plasma filtration, secondary membrane plasma fractionation can selectively remove undesired macromolecules, which then allows 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 employed as a therapeutic modality in a wide array of conditions. Generally, it is used when a substance in the plasma (eg, immunoglobulin) is acutely toxic and can be efficiently removed.Myriad conditions that fall into this category (including neurologic, hematologic, metabolic, dermatologic, rheumatologic, and renal diseases, as well as intoxications) can be treated with plasmapheresis.
The Apheresis Applications Committee of the American Society for Apheresis (ASFA) periodically evaluates potential indications for apheresis and categorizes them from I to IV in the basis of the available medical literature. The following are some of the indications, and their categorization, from the society’s guidelines.
The Apheresis Applications Committee of the American Society for Apheresis (ASFA) periodically evaluates potential indications for apheresis and categorizes them from I to IV in the basis of the available medical literature. The following are some of the indications, and their categorization, from the society’s guidelines.
Category I indications (disorders for which apheresis is accepted as first-line therapy, either as a primary standalone treatment or in conjunction with other modes of treatment) include the following:
Guillain-Barre syndrome
Myasthenia gravis (acute short-term treatment)
Chronic inflammatory demyelinating polyneuropathy
Hyperviscosity in hypergammaglobulinemia
Thrombotic thrombocytopenic purpura
Goodpasture syndrome (unless it is dialysis-dependent and there is no diffuse alveolar hemorrhage)
Thrombotic microangiopathy, complement mediated (autoantibody to factor H)
Wilson disease, fulminant
Category II indications (disorders for which apheresis is accepted as second-line therapy, either as a standalone treatment or in conjunction with other modes of treatment) include the following:
Lambert-Eaton myasthenic syndrome
Multiple sclerosis (acute central nervous system demyelination disease unresponsive to steroids)
Thyroid storm
Mushroom poisoning
Acute disseminated encephalomyelitis
Autoimmune hemolytic anemia (severe cold agglutinin disease)
Systemic lupus erythematosus (severe)
Myeloma cast nephropathy
Category III indications (disorders for which the optimal role of apheresis therapy is not established; decision-making should be individualized) include the following:
Posttransfusion purpura
RBC alloimmunization in pregnancy
Autoimmune hemolytic anemia (severe warm)
Hypertriglyceridemic pancreatitis
Thrombotic microangiopathy, complement mediated (complement factor mutations)
Stiff person syndrome
Drug overdose/poisoning
Immune thrombocytopenia
Category IV indications (disorders in which published evidence demonstrates or suggests apheresis to be ineffective or harmful; institutional review board [IRB] approval is desirable if apheresis treatment is undertaken in these circumstances) include the following:
HELLP syndrome (ante partum)
Hemolytic uremic syndrome (typical diarrhea-associated)
Multifocal motor neuropathy
Idiopathic polyarteritis nodosa
There is some evidence that plasmapheresis can be successfully used in patients to alleviate infection-related symptoms associated with antibody-dependent enhancement (ADE) of bacterial disease.
It has been suggested that plasmapheresis may be useful in the treatment of COVID-19 by removing cytokines and thus reducing the cytokine respons
As distinct from plasmapheresis, cytapheresis is the selective removal of RBCs, WBCs, or platelets and can be accomplished by using identical centrifuge-based equipment. Applications include the following:
Erythrocytapheresis (selective removal of RBCs) is used in conditions such as sickle cell disease or malarial infection, in which RBCs are selectively removed and replaced with donor erythrocytes.
HELLP syndrome (ante partum)
Hemolytic uremic syndrome (typical diarrhea-associated)
Multifocal motor neuropathy
Idiopathic polyarteritis nodosa
There is some evidence that plasmapheresis can be successfully used in patients to alleviate infection-related symptoms associated with antibody-dependent enhancement (ADE) of bacterial disease.
It has been suggested that plasmapheresis may be useful in the treatment of COVID-19 by removing cytokines and thus reducing the cytokine respons
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| Plasmapheresis/Plasma Exchange/Therapeutic Apheresis |
Technical Considerations
Although the term plasmapheresis technically refers only to the removal of plasma, it is also widely used to encompass therapeutic plasma exchange in which a replacement product is transfused after removal of the plasma.As distinct from plasmapheresis, cytapheresis is the selective removal of RBCs, WBCs, or platelets and can be accomplished by using identical centrifuge-based equipment. Applications include the following:
Erythrocytapheresis (selective removal of RBCs) is used in conditions such as sickle cell disease or malarial infection, in which RBCs are selectively removed and replaced with donor erythrocytes.
Leukapheresis (selective removal of WBCs) is used in conditions such as hyperleukocytosis, in which pathologically high number of white cells are present (as, for example, in leukemia); it can also be used to collect peripherally circulating stem cells that can then be infused in an autologous or allogeneic stem cell transplant.
Platelet apheresis (selective removal of platelets) can be used in conditions of thrombocytosis (eg, polycythemia vera).
Complication prevention
Having all the equipment and medications required for the procedure readily available at the start in order to minimize complications is important. Sterile technique is advised in order to reduce the likelihood of infection.Premedication with acetaminophen, diphenhydramine, and hydrocortisone are often given if the patient is to receive any blood product, including priming the tubing with packed RBCs, in particular if a history exists of prior reaction to blood products.
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