[2003][M609] INCREASE IN VON WILLEBRAND FACTOR DURING HEMODIALYSIS WITH BIO-INCOMPATIBLE MEMBRANES SUGGESTS ENDOTHELIAL ACTIVATION

Inge Wauters, Muriel Grooteman, Casper Schalkwijk, Piet ter Wee, Menso Nube. Department of Nephrology, Free University Medical Centre, Amsterdam, Netherlands.

Background:
Despite impressive improvements in dialysis treatment in recent years, cardiovascular mortality and morbidity remain high in chronic hemodialysis (HD) patients. In non-renal patients, increased plasma soluble von Willebrand Factor (vWF) is a marker of endothelial dysfunction and a strong predictor of cardiovascular disease. In HD patients, plasma levels of vWF are elevated, if compared to healthy controls. Sofar, it is not known whether HD treatment itself induces endothelial activation and contributes to the increase in vWF levels in this patient group. Therefore, vWF levels were assessed both intra-dialytical and in the longterm, during routine bicarbonate HD with four different dialysers.
Methods:
Fifteen stable chronic HD patients were cross-over randomised to be treated with four different dialysers: superflux polyethersulfone (PES; Syntra 160g), high flux polysulfone (PS; F70S), low flux polysulfone (PS; F7HPS) and a low flux cuprammonium (CU; AMD-750 USD) dialyser, for a period of 4 weeks. All dialysers had comparable surface-areas and were not ETO-sterilised. To exclude carry-over effects, a washout period of 2 weeks on low flux PS was instituted between each treatment period. Blood samples were drawn from the arterial line at the start of HD before each treatment period (baseline), and after 4 weeks at the start of HD (t0) and after 4 hours (t240). vWF was assessed in EDTA-plasma using an ELISA-technique
Results:
vWF levels varies considerably between different HD patients. The mean maximal difference between individuals was 20660%, whereas the mean difference within individuals was 12867%. During dialysis with CU, vWF levels increased significantly (from 18848% at t0 to 24586% at t240, p<0.01), wich was highly different from PS (CU 5563%, PS 856%, p=0.013). Differences were not observed between the low flux, high flux and super flux modalities. After 4 weeks of HD on each dialyser, vWF levels were similar to baseline.
Conclusion:
In the present study, HD with CU dialysers induced a marked increase in vWF levels, which was not observed after HD with low flux, high flux, or super flux biocompatible materials (PS and PES). These results suggest that complement activation products play an important role in the activation or damage of the endothelium during HD. Furthermore, patient factors rather than the type of dialyser appeared to be responsible for baseline vWF values. Hence, our findings indicate that both patient factors and HD treatment with bio-incompatible complement-activating membranes contribute considerably to the elevated vWF levels in chronic HD patients.
Keywords: haemodialysis: biocompatibility; complement system; coagulation system; haemodialysis: outcome

Poster Session: ESRD treatment comparisons