• Filippo Mariano, Valentina Fonsato, Giacomo Lanfranco, Robert Pohlmeier, Claudio Ronco, Giorgio Triolo, Giovanni Camussi, Ciro Tetta, and Jutta Passlick-Deetjen.
• Department of Medicine Area, Nephrology and Dialysis Unit, CTO Hospital, Turin 10126, Italy. filippo.mariano@poste.it
• Nephrol. Dial. Transplant. 2005 Jun 1;20(6):1116-26.

BackgroundAs removal of pro-inflammatory cytokines is limited in conventional diffusive or convective extracorporeal therapies, we studied in two polysulphone membranes with an industrial albumin sieving coefficient of 0.05 (Type A) and 0.13 (Type B) cytokine (IL-6, IL-8, IL-1beta, IL-1ra, TNF-alpha) and plasma protein (albumin, cystatin C, total proteins) permeability profiles. Based on the convective membrane permeability, we evaluated in vitro the dialytic modality that could provide an acceptable balance between high cytokine and low albumin clearances.MethodsCytokine and plasma protein sieving coefficient (SC) and clearance were studied in (i) post-dilutional haemofiltration mode at 20% fixed ultrafiltration rate; (ii) haemodialysis mode (dialysate flow rate of 3 and 5 l/h); and (iii) haemodiafiltration mode (dialysate flow rate of 3 or 5 l/h with 0.5 l/h of ultrafiltrate).ResultsIn haemofiltration mode both Type A and Type B haemodialysers at QB 150 ml/min exhibited similar median SC nearly up to 1 for IL-1beta and IL-1ra, at about 0.6 for IL-6, 0.4 for IL-8 and 0.7 for TNF-alpha, with clearance values ranging from 15 to 30 ml/min. SC were independent of blood flow and were stable throughout the whole experiment. Albumin SC was higher in Type B than in Type A and rapidly decreased from 0.2 to 0.02 and from 0.5 to 0.04 within 3 h for haemodialyser Types A and B, respectively. Cytokine SC was lower in haemodialysis than in haemodiafiltration and haemofiltration mode, and by increasing dialysate flow from 3 up to 5 l/h in both haemodialysis and haemodiafiltration mode, SC for all tested cytokines decreased. However, at 5 l/h clearances were not different or were higher, since increased amounts of dialysate outlet compensated for the decreased SC. Albumin clearances in haemodialysis and haemodiafiltration mode after 360 min at 5 l/h were 0.81 and 0.91 ml/min, respectively.ConclusionsOur studies show that a mixed convective and diffusive technique ensures high cytokine clearances with an acceptable loss of albumin.

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