The effects of increasing the convective clearance of uremic toxins using high-efficiency on-line hemodiafiltration (ol-HDF) on vascular function and structure in end-stage renal disease (ESRD) patients remain unknown.

Forty-two ESRD patients were randomized to switch from high-flux hemodialysis (HD) to ol-HDF (n=22) or to continue HD (n=20) for 4 months in a prospective double-blind study. Brachial artery endothelium-dependent flow-mediated dilatation (FMD), carotid artery structure and stiffness, and cardiovascular coupling, uremic toxins (beta-2 microglobulin, phosphatemia) and circulating markers of inflammation (TNF and inducible NO-synthase blood mRNA) and oxidative stress (reactive oxygen species, total antioxidant status) were assessed at baseline and at follow-up.

FMD increased in patients on ol-HDF (152±27 to 177±34 m, P=0.002) but not in patients on HD (165±46 to 161±36 m, P=0.25; P<0.01 vs. ol-HDF). Peripheral and central blood pressures, augmentation index, carotid artery diameter and intima-media thickness remained stable in both groups Carotid distensibility was higher (P=0.04 vs. HD) and elastic modulus tended to be lower (P=0.09 vs. HD) in patients on ol-HDF. Beta-2 microglobulin (P=0.02) and phosphatemia (P=0.01) decreased in patients on ol-HDF. Moreover, in patients on ol-HDF, there was a trend for a decrease in inducible NO-synthase (P=0.07) and plasma nitrite (P=0.06), a marker of NO availability, while TNF increased only in patients on HD (P=0.04; P=0.01 vs. ol-HDF). Oxidative stress markers remained stable in both groups.

High-efficiency ol-HDF improves endothelial function and decreases arterial stiffness in ESRD patients as compared with high-flux HD. This may be notably related to the reduction in uremic toxins and vascular inflammation.