Plasmapheresis is a therapeutic procedure for removing unwanted proteins, immunoglobulins, or antibodies from human blood plasma. This filtering process, which takes place outside the body, can favorably influence the course of various diseases or even cure them.
What is plasmapheresis?
Plasmapheresis is a therapeutic procedure for removing unwanted proteins, immunoglobulins, or antibodies from human blood plasma. The term pheresis comes from the Greek and means taking away a part of the whole. In plasma exchange, which is always used for therapy, the separated part of the plasma is discarded and replaced by another volume fluid, depending on the indication. In the majority of cases, this is physiological saline or Ringer’s solution. The procedure is also referred to as therapeutic plasma exchange, although not all of the blood plasma is exchanged, but only unwanted components, usually containing protein, are filtered out. Although plasma separation can also trigger negative side effects, these are usually accepted because the benefit for the individual patient is incomparably greater. In English, plasmapheresis is also referred to as plasma exchange, PE. It is an established medical procedure that is subject to high scientific standards and has been further optimized and refined in recent years in order to meet the various indications as precisely as possible. The proven therapy procedure can be successfully performed under outpatient, semi-outpatient or even inpatient conditions.
Function, effect, and goals
The very first purpose of therapeutic plasma exchange is to remove unwanted components in the fluid components of the flowing blood. The cellular components of the blood, i.e., all blood cells such as erythrocytes, leukocytes, or platelets, are not altered during plasmapheresis. It is exclusively a matter of therapeutically influencing the composition of the blood plasma. If the aim is the effective removal of unwanted antibodies as high-molecular proteins, then plasmaseparation is used particularly in neurology or renal medicine, nephrology. If the procedure is used specifically for lipid metabolism disorders, doctors also refer to it as lipid apheresis. The filtration process can then be adjusted in such a way that only unwanted microscopic fatty bodies, lipids, are removed from the blood plasma. Plasma exchange is thus a selective process in which only the unwanted plasma components should ever be removed. Of course, this is not always possible under all circumstances, because it may also result in the removal of components in the plasma that should not actually be removed. This is precisely the reason why there may be certain risks and dangers for the patient. Similar to hemodialysis, plasmapheresis is a so-called detoxification procedure. The body is thus to be freed or detoxified of those substances that would otherwise accumulate in the plasma. How often and at what intervals a therapeutic plasma separation must be carried out depends strictly on the respective indication and the clinical picture. According to medical-scientific criteria, there are confirmed, suspected and questionable treatment indications for the procedure. It is considered certain that plasmapheresis in the so-called hemolytic-uremic syndrome as well as in thrombotic thrombocytopenic purpura is very helpful for the patient to regain or maintain his quality of life. Presumed indications justifying the performance of therapeutic plasma exchange are certain renal diseases, so-called glomerulopathies, and systemic lupus erythematosus. Both chronic diseases are so-called autoimmune diseases, i.e. antibodies are formed in an uncontrolled manner against the body’s own tissue structures. By means of plasmapheresis, these tissue-damaging antibodies can be temporarily removed from the patient’s body. Questionable indications are pemphigus vulgaris, a skin disease associated with the formation of harmful autoantibodies, and multiple sclerosis.Particularly in the case of an acute attack with disease value and worsening of the prognosis, a therapeutic plasma exchange in multiple sclerosis can be worthwhile for the patient. However, by no means all patients suffering from this chronic inflammatory disease of the central nervous system benefit from it.
Risks, side effects, and hazards
To perform the separation of blood components therapeutically, so-called cell separators are required. This process takes place outside the body in specially designed machines. Modern cell separators all have computer-controlled valves and roller pumps. Absolutely sterile operation is essential, because in all blood exchange procedures the greatest danger to the patient is from possible infections. In plasmapheresis in particular, vital components such as coagulation factors are removed from the plasma in addition to undesirable low-molecular-weight components such as autoantibodies or pathological proteins. The clotting factors are produced in the liver and cannot, however, be replenished as quickly as they are removed by plasma separation. In many cases, therefore, it is necessary to add artificial clotting factors to the purified plasma so that the blood’s clotting ability is not impaired. It is essential to prevent a permanent bleeding tendency of the patient due to a therapeutic plasma exchange. Special semipermeable membrane plasma separators are needed to filter out only certain fractions of individual proteins during the process. Membrane testing in vitro can be used to determine exactly which sizes of molecules can pass through the membrane and which will be retained prior to patient use. In plasmapheresis, both blood collection and retransfusion are performed through the same venous access, such as an arm vein. With each retransfusion, reinfusion, the cellular components, i.e., the different blood cells, are returned to the patient in addition to the purified plasma.
