apheresis: a procedure in which blood is drawn and separated into its components by dialysis; some are retained and the rest are returned to the donor by transfusion
dialysis: separation of substances in solution by means of their unequal diffusion through semipermeable membranes
attractor: (physics) a point in the ideal multidimensional phase space that is used to describe a system toward which the system tends to evolve regardless of the starting conditions of the system