Also known as plasmapheresis; the removal of the circulating plasma from the patient. It is done by removing blood from a patient and returning the red cells with a plasma expander. The plasma exchange is carried out through an in-dwelling cannula in the femoral vein, and the red cells and plasma are separated by a hemonetics separator. Usually a sequence of three or four sessions is undertaken, at each of which 2-3 litres of plasma are removed. The lost plasma can either be replaced by human serum albumin or a plasma expander.