Therapeutic apheresis involves passing blood through a machine in order to remove harmful components. Blood is drawn through a tube placed in a patient's vein before entering a machine which separates the blood into its different parts using a centrifuge. Those parts of the blood which are associated with disease are extracted and thrown away. This leaves only healthy blood, which is returned to the patient through another tube. Apheresis can also be used to harvest stem cells from the blood for transplant into a cancer patient, a process known as peripheral stem cell transplantation.
One of the benefits of therapeutic apheresis is that it takes only a few hours to perform, typically up to four. Patients are not required to stay in the hospital after these types of therapeutic treatments, although another person will normally have to drive them home. As therapeutic apheresis is associated with calcium loss, it is important to consume plenty of calcium on the days before the treatment. Patients are allowed to eat and drink on the morning before the procedure. During therapeutic apheresis, two tubes connect the patient to the machine, although they may be combined into one catheter with two channels inside.
Therapeutic apheresis can be used to treat a number of conditions. It is often used to remove molecules such as antibodies from the blood. Although antibodies are part of the immune system and help protect the body from harmful invaders such as bacteria, sometimes their production may become abnormal. This can result in what are known as autoimmune diseases, such as myasthenia gravis, where antibodies block muscle cell receptors, preventing nerve signals from reaching them. Although the cause is unknown, myasthenia gravis can be associated with tumors of the thymus gland.
In myasthenia gravis, muscle weakness develops, and this can have serious consequences if the respiratory muscles are affected. If breathing difficulties occur, therapeutic apheresis may become necessary. Apheresis is carried out to remove the blocking antibodies from blood plasma. Replacement plasma from a donor, which is free from antibodies, may then be given to the patient. Using therapeutic apheresis in this way can reduce the symptoms of myasthenia gravis for a number of weeks, and it is one of the therapeutic treatments which may be performed before the thymus is surgically removed.
Some possible side effects of therapeutic apheresis include bruising where the needles enter the skin, tingling lips, feeling light-headed and cold. Sometimes itching and hives may develop, and blood pressure could fall. It is important to rest after treatment, to drink plenty of fluids and avoid strenuous activities.