Therapeutic hemapheresis

Therapeutic hemapheresis includes plasmapheresis and cytapheresis, which are usually tolerated in healthy donors. However, there are many minor and a few significant risks. The placement of venous catheters required for hemapheresis may cause complications (bleeding, infection, pneumothorax). Citrate anticoagulant may decrease serum ionized calcium. Plasma replacement with noncolloidal solutions (eg, saline) results in fluid shift to the extravascular space. Colloidal solutions do not replace IgG and sequestering factors.

Most complications can be controlled with close patient monitoring and adjustment of procedural parameters, but some severe reactions and isolated deaths have been reported.

Plasmapheresis

Therapeutic plasmapheresis removes plasma components from the blood. A blood cell separator removes the patient's plasma and returns red blood cells and platelets or plasma-substituting solutions; for this purpose, 5% albumin is preferred over fresh frozen plasma (except in patients with thrombotic thrombocytopenic purpura) because albumin causes fewer transfusion reactions and is not a vector for infection. Therapeutic plasmapheresis is similar to dialysis but can additionally remove protein-bound toxic substances. Exchange of one volume of plasma removes about 66% of such components.

To be effective, plasmapheresis must be used in diseases where the plasma contains known pathogenic substances and plasmapheresis can remove these substances faster than the body produces them. For example, in rapidly progressing autoimmune diseases, plasmapheresis can be used to remove harmful plasma components (e.g., cryoglobulins, antiglomerular antibodies), while immunosuppressive or cytotoxic drugs impair their production. There are numerous indications for plasmapheresis. The frequency of plasmapheresis, the volume of plasma removed, the type of replacement solution, and other parameters are individual. Low-density lipoprotein cholesterol can be removed by plasmapheresis using a recently proposed instrumental filtration method. Complications of plasmapheresis are similar to those of therapeutic cytapheresis.

Indications for plasmapheresis according to the American Society of Apheresis and Transfusion Medicine guidelines

Category	Plasmapheresis	Cytapheresis
I. Standard measures recommended in certain circumstances, including primary therapy	Acute inflammatory demyelinating polyradiculoneuropathy. A disease caused by antiglomerular antibodies. Chronic inflammatory demyelinating polyradiculoneuropathy. Demyelinating polyneuropathy with IgG/IgA. Myasthenia gravis. Phytanic acid storage disease. Post-transfusion purpura. Thrombotic thrombocytopenic purpura	Cutaneous T-cell lymphoma: photopheresis. Erythrocytosis/polycythemia vera. Familial hypercholesterolemia: lipid absorption Hyperleukocytosis: leukodepletion. Sickle cell anemia: erythrocyte metabolism. Thrombocytosis: platelet depletion
II. Recommendations with sufficient evidence of efficacy; acceptable as adjunctive treatment	ABO incompatible bone marrow transplant (recipient). Acute inflammatory demyelinating disease of the central nervous system. Coagulation factor inhibitors. Cryoglobulinemia. Cryoglobulinemia with polyneuropathy. Familial hypercholesterolemia. Eaton-Lambert syndrome. Myeloma/acute renal failure. Myeloma/paraproteins/hyperviscosity/PANDAS (pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections). Polyneuropathy with IgM (+ Waldenstrom). Rapidly progressive glomerulonephritis. Chorea	Chronic graft-versus-host disease: photopheresis. Erythrocytosis/polycythemia vera: depletion of red blood cells. Hyperparasitemia - malaria. Babesiosis: erythrocyte metabolism. Idiopathic thrombocytopenic purpura: immunoadsorption. RA: immunoadsorption

Cytapheresis

Therapeutic cytapheresis removes cellular components from the blood, returning the plasma. It is most often used to remove defective red blood cells and replace them with normal ones in patients with sickle cell anemia in the following conditions: acute coronary syndrome, stroke, pregnancy, frequent crises. Cytapheresis achieves a decrease in HbS levels to < 30% without the risk of increasing blood viscosity, which can occur with conventional transfusion. Therapeutic cytapheresis can be used to reduce severe thrombocytosis or leukocytosis (cytoreduction) in acute or chronic leukemia when there is a risk of bleeding, thrombosis, pulmonary or cerebral complications caused by high leukocytosis (leukostasis). Cytapheresis is especially effective in thrombocytosis, because platelets are not replaced as quickly as leukocytes. One or two procedures reduce the platelet level to a safe level. Therapeutic reduction of white blood cell count (leukapheresis) can remove kilograms of buffy coat in a small number of procedures, often reducing leukostasis and splenomegaly. However, the reduction in white blood cell count is only small and short-lived.

Another indication for the use of cytapheresis is the collection of peripheral blood stem cells for autologous or allogeneic transplantation, and the collected lymphocytes are used for immunomodulation in cancer therapy.

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