ULTRAFILTRATION AND ENDOTOXIN REMOVAL FROM DIALYSIS FLUIDS

Biocompatibility in hemodialysis is now regarded as a multifactorial p roblem and dialysate represents a main risk. Pyrogenic fractions mostl y coming from gram-negative bacteria easily pass through dialysis memb rane, either by backdiffusion or by backfiltration, and induce blood c ell activation. To demonstrate the long-term efficiency of a 2 M2 poly amide ultrafilter in producing a pyrogen free solution, we used an exp erimental circuit ultrafiltering for 240 hours (500 ml/min) a bicarbon ate dialysate contaminated (5 to 48 EU/ml) by a Pseudomonas aeruginosa filtrate. The efficiency was monitored by LAL-test and IL-1 PBMC so t o detect not only lipid A containing endotoxins but also other cytokin es inducing bacterial fractions. At the post-ultrafilter sampling port the LAL-test was <0.005 to 0.034 EU/ml; IL-1 PBMC was below the detec tion limit (20 pg/ml) being 27 to 63 pg/ml at the pre-ultrafilter leve l. Polyamide ultrafiltration represents an efficient system to obtain an endotoxin-free dialysate and a single filter works up to 240 hours.