Plasmapheresis
From Noblood
Treats illness
Plasmapheresis (from the Greek plasma, something molded, and apheresis, taking away) is the removal, treatment, and return of (components of) blood plasma from blood circulation. It is thus an extracorporeal therapy.
Description
During plasmapheresis, blood is initially taken out of the body through a needle or previously implanted catheter. Plasma is then removed from the blood by a cell separator. Some physicians may want to use plasma from another person to replace that from the patient's blood. Three procedures are commonly used to separate the plasma from the blood:
- Discontinuous flow centrifugation - One venous catheter line is required. Typically, a 300 ml batch of blood is removed at a time and centrifuged to separate plasma from blood cells.
- Continuous flow centrifugation - Two venous lines are used. This method requires slightly less blood volume to be out of the body at any one time as it is able to continuously spin out plasma.
- Plasma filtration - Two venous lines are used. The plasma is filtered using standard hemodialysis equipment. This continuous process requires less than 100 ml of blood to be outside the body at one time.
Each method has its advantages and disadvantages. After plasma separation, the blood cells are returned to the person undergoing treatment, while the plasma, which contains the antibodies, is first treated and then returned to the patient in traditional plasmapheresis. (In plasma exchange, the removed plasma is discarded and the patient receives replacement donor plasma or saline with added proteins.) Medication to keep the blood from clotting (an anticoagulant) is generally given to the patient during the procedure. Plasmapheresis is used as a therapy in particular diseases. It is an uncommon treatment in the United States, but it is more popular in Europe and particularly Japan.
