The influence of the geometry of the dialyzer and the composition of the dialysate in activating the complement system.

During hemodialysis there is a complex interaction between the patient and the extracorporeal circuit that activates the complement system, among others. To better understand the influence of the dialyzer geometry and the dialysate composition, we compared hollow fiber versus parallel plate dialyzers and acetate versus bicarbonate dialysates and their role in the production of C3a, C4a and C5a. There was no significant difference in the plasmatic levels of these anaphylotoxins and their des-Arg derivates, as measured by RIA, in either dialyzer. The same was true when the dialysate in question had a different composition. We thus concluded that neither the geometric configuration of the dialyzer nor the composition of the dialysate influence their biocompatibility as regards the activation of the complement system, and that the differences that have been described shall have to be explained in another manner or assessed by methods other than those used in this study.