Comparison of the new polyethersulfone high-flux membrane DIAPES® HF800 with conventional high-flux membranes during on-line haemodiafiltration

Background. Current modalities of renal replacement therapy allow only a limited removal of larger, possibly toxic molecules, which accumulate in uraemia. Recently, a haemodiafilter has been made available with the new, high-flux, polyethersulfone-based membrane DIAPES(R) HF800. We performed a study to compare DIAPES(R) HF800 with two conventional high-flux membranes in on-line haemodiafiltration (HDF), with respect to the removal properties for the two marker proteins, beta(2)-microglobulin (beta(2)m, 11.8 k Da) and albumin (66.5 kDa). Methods. In a prospective, controlled study 10 stable end-stage renal disease patients were randomly allocated to 30 sessions of post-dilutional on-line HDF with three types of steam-sterilized membranes: DIAPES(R) HF800, polysulfone and polyamide. Blood flow rate was 250 ml/min and treatment time was 240 min. Pre-treatment beta(2)m and albumin plasma concentrations did not differ between the three groups. The concentration of the two proteins was determined before and after treatment in plasma as well as in the continuously collected haemodiafiltrate. Results. Tolerance of all treatments was very good, without any side-effects for all filters. The mean plasma reduction rate of beta(2)m was 77 +/- 1% for DIAPES(R) HF800 and polysulfone whereas it was 71 1% for polyamide (P < 0.05). The mean beta(2)m amount removed and found in the haemodiafiltrate per session was 230 +/- 14 mg for DIAPES(R) HF800, 186 +/- 13 mg for polysulfone and 147 +/- 13 mg for polyamide (P < 0.05 between each pair of membranes). The same ranking was obtained for albumin removed and found in haemodiafiltrate per session for the three membranes: 5.7 +/- 0.4, 3.5 +/- 0.4 and 1.0 +/- 0.4 g, respectively. Although DIAPES(R) HF800 showed the highest value for albumin in haemodiafiltrate the mean post-treatment plasma albumin was higher after the treatment with DIAPES(R) HF800 compared with the other membranes (P < 0.05). Conclusions. On-line HDF has shown to achieve plasma reduction rates for beta(2)m of up to 77% for the DIAPES(R) HF800 membrane and for polysulfone. The amounts of beta(2)m and albumin in haemodiafiltrate were much higher for DIAPES(R) HF800 than for the other two membranes indicating a greater permeability for molecules up to a molecular weight of 66.5 kDa. This could, at least theoretically, offer the advantage also to remove uraemic toxins in the molecular weight range of albumin or of albumin-bound toxins. The future must show whether this will counterbalance the loss of albumin.