The possibility of reducing bioreactivity during extracorporeal circulation by removing bioactive substances “turned on” in the devices is described in this paper. The bioreaction and bioactive products, as represented by neutrophil reaction and activated complement fragments generated during the use of a blood-perfused artificial organ, were studied as a model. Hemoperfusion with activated charcoal (AC) was used to remove the activated complement fragments. The adsorption of anaphylatoxins (C3a, C4a, and C5a) was evaluated following plasma perfusion through AC in vitro, all three of which were satisfactorily adsorbed. Six kinds of AC (three HEMA coated AC, two uncoated AC, and one cellulose coated AC) were compared with respect to adsorption of C5ain vitro. Uncoated AC adsorbed well and rapidly, but the coating with HEMA made adsorption take place slowly. The cellulose coating activated complement and did not decrease plasma C5a levels. After the adsorption of anaphylatoxins was confirmed, each of the AC columns was placed on-line after a coprophan dialyzer in five chronic hemodialysis patients. C3a, levels and neutrophil counts were compared with those obtained during usual hemodialysis (HD). By using heparin treated, uncoated AC, elevation of C3a levels and transient neutropenia were suppressed. Peak C3a with AC was reduced by 150% compared with prevalues, and the neutropenia nadir increased from 20% to 40% of baseline. The adsorption ability influenced the reduction in neutropenia. The heparinized uncoated AC and the column with large volumes of HEMA-coated AC had the best effect. The ability to reduce the bioreaction occurring in artificial organs was demonstrated, suggesting that biocompatibility of an artificial organ should not be evaluated with respect to separate materials but to the device as a whole.
©1989 American Society of Artificial Internal Organs