Exchange Transfusion

Excerpt

Therapeutic plasma exchange (TPE) is a procedure in which blood or plasma is separated, removed, and replaced with a colloid solution of either albumin and/or donor plasma so as to accomplish the elimination of a pathologic entity. Plasma is exchanged in volumes, usually between 1 to 1.5 L to remove dysfunctional cells, autoantibodies, immune complexes, cellular byproducts, parasites/bacteria, and toxins. There are two different methods for plasma separation - manual and automated.

The manual method consists of phlebotomizing a patient, centrifuging the blood to separate plasma from cellular components, extracting the plasma, and then returning the cellular components back to the patient. The automated method involves the use of a plasmapheresis machine, which accomplishes the same functions as the manual method in a continuous flow extracorporeal circuit. The removal and replacement of plasma cause an overall dilution for which one volume exchange clears 66% of target constituents and 85% with a second and 93% with a third. The efficiency of TPE in eliminating the undesired entity is dependent on mass, production rate, and location in the blood (intracellular vs. extracellular) of said entity.