Biocompatibility aspects of dialyzer reprocessing: a comparison of 3 re-use methods and 3 membranes

While formalin reprocessing of cuprophan dialyzer membranes is known to improve their biocompatibility, the effects of different re-use methods have not been systematically investigated on different membranes. Therefore, the effects of reprocessing with formalin, hypochlorite-formalin and peracetic acid were successively investigated in 3 groups of 4 patients dialyzed on cuprophan (CU), cellulose acetate (CA) or polysulfone (PS). Leukocyte count, thrombocyte count and complement activation were studied during second and third use of the dialyzer. Formalin 3% storage was found to improve leukopenia, thrombocyte count and complement activation on CU but not on PS or CA where leukocyte and thrombocyte count worsened. Hypochlorite 1% rinsing prior to formalin 3% storage abolished the improvements observed on CU with formalin and induced on CA and PS the same leukopenia as formalin. In contrast, peracetic acid storage improved leukopenia, complement activation and thrombocyte count on the 3 membranes. In addition, it was found that storage of plasma-treated membrane fragments with peracetic acid abolished neutrophil oxygen radical production. Thus it appears that re-used membranes may not be systematically assumed to be more biocompatible, this property varying with both the type of membrane and the reprocessing technique.