Complications of hemoperfusion

Hemoperfusion (1) is the technique of passing blood through a bed of particles contained within a device, usually cylindrical, to which blood lines and a blood pump are attached (Fig. 1A). It differs (1) from hemodialysis in that blood comes in direct contact with the membrane-coated sorbent particle and not a continuous dialysis membrane, and (2) from plasmapheresis in that no plasma is separated from blood. Hemoperfusion can be combined with any renal replacement therapy, usually hemodialysis, to increase efficiency and maintain the temperature of blood (Fig. 1B). The particles are usually inorganic (activated charcoal, neutral or ion exchange resins), but devices under development may contain cells on the dialysate side of a hemodialysis membrane [hepatosomes (2) or renal tubule cells (3)], immobilized antibiotics for removal of endotoxin [polymyxin B (4)], immobilized antibodies (5), or coated gets (6). Some similar commercially available systems use fluidized sorbents in dialysis fluid (charcoal and a cation exchanger) on one side of a cellulosic dialysis membrane (7,8) or sorbents coupled with “push-pull” plasma exchange to allow direct contact of plasma with sorbents for removal of toxins in hepatic failure (9); the main advantage over direct contact hemoperfusion is the absence of thrombocytopenia since contact of blood is restricted to the hemodialysis/pheresis membrane. This discussion will focus on inorganic hemoperfusion in light of the paucity of clinical reports of developmental devices.