Sterile filtration of dialysate: is it really of no use?

In 1972, Raij et al. reported the occurrence of circulating endotoxins in patients with febrile reactions at the end of dialysis sessions and, in parallel, high endotoxin levels in the dialysate w2x. Even nowadays, neither tap water nor purified water or dialysate are sterile. In more than 14 000 analysed water probes of city and village water systems in South-West Germany, 5.6% contained coliform bacteria and 3.6% contained Escherichia coli w3x. Recently, Arvanitidou et al. found E. coli in 12% of tap water samples in a study of all Greek dialysis centres w4x. Because of the more frequent use of high-flux dialysis membranes, the role of endotoxin and, in particular, endotoxin fragments in the water used for dialysis or the dialysate has been reassessed during recent years. In this context, the American Association for the Advancement of Medical Instrumentation (AAMI), and Swedish and German legislation have reduced acceptable endotoxin concentrations in pure water to the range of 0.25–1.0 EUuml. Multicentre controls of dialysates in German dialysis centres showed that only 14–23% of samples contained less than 1.0 EUuml, and concentrations between 100 EUuml and )400 EUuml were found in about 10% of dialysate probes w5x. Similar results have been reported during the last decade, from various other countries by several authors w6–8x. Role of dialysis, machine and dialyser