Microsoft Word - NEF117BF

Prof. M. Fischbach, Unité Nephrologie Dialyse, Transplantation, Pédiatrie 1, Hôpitaux Universitaires de Strasbourg Hautepierre, F-67000 Strasbourg (France) Patient Dear Sir, Microbially contaminated dialysate is a well-known risk in patients undergoing he-modialysis but today seems very infrequent. On the contrary, more attention is to take into consideration for the dialysate pyrogenic substances, or endotoxins, with the introduction of high-flux dialysis (hydraulic and molecular highly permeable membranes, dialysate retrofiltration phenomenon) and especially during hemodiafiltration with on-line dialysate filtration (production from the dialysate of substitution fluid or infusate for hemofil-tration) [1]. Many authors have tested the permeability of highly permeable polysulfone membranes for pyrogens, mostly with highly sensitive methods (Limulus amebocyte lysate assay, LAL, or interleukin 1, IL-1) [2-4,]. Recently, Frinak et al. [5] have demonstrated the effectiveness of the on-line polysulfone filtration system for the removal of pyrogenic substances from dialysate with high microbial burden. But we feel that this dialysate purification method is only a reduction factor of contamination. In this way, we have performed a study in vitro with on-line dialysate filtration (fig. 1). The dialysate, in recirculation use, is contaminated by high rates of free endotoxins (lipopolysaccharide preparation, LPS, Escherichia coli 0111 B4 L 4130, Sigma France) to reach a 5,000-ng/ml concentration. On-line hemodiafiltration (infusate for hemofiltration flow rate 100 ml/min) is conducted during 180 min with samples on sites 1 and 2. Each sample (0, 10, 30,90,180 min) is analyzed (double determination) by two methods: firstly, the LAL test (sensibility 0.03 ng/ml; Pyrotel, Ami-labo), secondly, the polyacrylamide electrophoresis technique (sensitivity 25 ng/ml) described by Hitchcock [6]. Dialysate Fig. 1. In vitro on-line hemodiafiltration. Patient: pyrogen-free physiological serum bag (1,000 ml), flow rate 150 ml/min. Dialysate: recirculation 5,000 ml, flow rate 600 ml/min. 1,2 = Dialysate samples after 1 or 2 polysulfone membrane ultrafiltrations. at each time of the study, but a crossing through the membrane was identified by an LAL test at 10 min.