Plasma exchange therapy, also known as plasmapheresis or therapeutic plasma exchange, is a medical procedure that cleanses the blood. It involves removing a patient’s plasma, the liquid portion of blood, to eliminate harmful substances like abnormal antibodies, toxins, or immune complexes that contribute to various diseases. This selective removal aims to alleviate symptoms and improve health.
The Role of Plasma
Plasma is the liquid component of blood, carrying essential elements throughout the body. It transports blood cells, proteins, electrolytes, nutrients, hormones, and waste products. Plasma also helps maintain blood pressure and regulate body temperature. In certain diseases, plasma can harbor harmful components like abnormal antibodies or toxins, disrupting normal bodily functions. Removing this problematic plasma is a strategy to manage conditions where these harmful substances accumulate.
How Plasma Exchange is Performed
The process of plasma exchange utilizes a specialized machine, often referred to as an apheresis machine, to separate the blood components. Blood is drawn from the patient, typically through a large vein in the arm or a central venous catheter inserted into a larger vein in the neck or chest. The apheresis machine then centrifuges the blood or uses a filtration method to separate it into its distinct parts: red blood cells, white blood cells, platelets, and plasma. The diseased plasma, containing the harmful substances, is discarded.
After the patient’s plasma is removed, the remaining blood cells are combined with a healthy replacement fluid. This substitute can be a solution containing albumin, saline, or, in some cases, donor plasma. The reconstituted blood, now free of harmful components, is then returned to the patient’s body. This continuous cycle effectively removes problematic plasma while returning essential blood cells.
Conditions Benefiting from Plasma Exchange
Plasma exchange therapy is employed for conditions where harmful plasma substances contribute to disease. Autoimmune diseases, where the immune system mistakenly attacks the body’s own tissues, often benefit. For instance, in Guillain-Barré syndrome, plasma exchange removes autoantibodies that damage nerve cells, potentially improving neurological function. Similarly, in Myasthenia Gravis, removing antibodies that interfere with nerve-muscle communication can reduce muscle weakness.
The therapy is also used for specific blood disorders, such as thrombotic thrombocytopenic purpura (TTP), where it removes factors causing abnormal blood clot formation. Certain kidney disorders, like Goodpasture syndrome, also respond to plasma exchange by clearing harmful antibodies that attack kidney tissue. Other conditions, including systemic lupus erythematosus (SLE), cryoglobulinemia, and chronic inflammatory demyelinating polyneuropathy (CIDP), also show improvement.
Preparing for and Recovering from Treatment
Preparing for plasma exchange involves several steps to ensure patient safety and optimize the procedure. Patients might need to adjust medications before treatment, and adequate hydration is often recommended. For those without suitable peripheral veins, a central venous catheter may be inserted prior to the first session for reliable access. During a session, which typically lasts two to four hours, patients are continuously monitored.
While generally well-tolerated, patients may experience some common side effects. These can include a temporary drop in blood pressure or a tingling sensation, often due to the anticoagulant (citrate) used to prevent blood clotting. Fatigue is also a common post-treatment experience. After a session, patients are advised to rest, and proper care of the access site is important to prevent complications. Follow-up sessions are scheduled based on the condition and patient response, often occurring every few days over several weeks.