Apheresis

The term Apheresis is Greek in origin and it means 'to take away'. This is a medical technology wherein the blood of a donor/patient is passed through an apparatus that separates one particular required component. The separated portion is withdrawn and the remaining components are retransfused into the patient/donor. The components thus separated from the patient/donor includes, plasma, platelets or leukocytes. This procedure is adhered to as an extracorporeal therapy.

In the process of apheresis, whole blood is removed from the patient/donor. The components of whole blood are separated by a centrifuge or an instrument specially designed for this purpose. The apheresis procedure is often employed to obtain stem cells from peripheral blood of patients suffering leukemia, a blood disease. Stem cells are infused into the patient's blood stream in order to produce cells that eventually will mature into red blood cells, white blood cells and platelets.

In transplants such as bone marrow procedures, the sick person happens to be his/her own donor. Blood is drawn and at a later time reinfused into that patient's blood stream in a procedure known as autologous bone marrow transplant. When stem cells are obtained from a healthy person, the procedure is allogeneic bone marrow transplant. Here, another person, may or may not be related, is the donor. Apheresis has become essential in providing blood components for several types of therapies. The process of apheresis takes a couple of hours and the volunteer donor/patient undergoes apheresis to supply specific components.

Leukapheresis is the removal of PMNS (Polymorphonuclear leukocytes), basophils and eosinophils for transfusion into patients whose PMNs are ineffective or in whom the traditional line of therapy has failed. LDL apheresis is the removal of low density lipoprotein in patients suffering from hypercholesterolemia. Erythrocytapheresis is the collection of red blood cells (RBCs) either two standard units of RBCs or one unit plus either plasma or platelets. This process is commonly known as 'double reds' or 'double red cell apheresis'.

Apheresis is used in stem cell harvesting for circulating bone marrow cells during transplantations. To collect sufficient stem cells, apheresis process is performed for at least two consecutive days, although at times five or even more procedures become necessary.

It is pertinent to understand that when apheresis system is adopted for therapy, the system is removing relatively small amounts of fluid, not more than 10.5 mL/kg body weight. That fluid which is removed must be replaced in order to maintain the intravascular volume.
The apheresis process is painless. Some patients/donors may experience lightheadedness, numbness or tingling of the nose, lips or fingers. These symptoms are short lived and treatable. Possible complications include bleeding in needle sites, thrombosis or clotting in blood vessels, or rarely surgical complications if a temporary apheresis catheter is inserted. Infection is always a risk as this procedure involves penetrating the skin and open access to blood vessels.