Combining Diffusion, Convection and Absorption: A Pilot Study of Polymethylmethacrylate versus Polysulfone Membranes in the Removal of P-Cresyl Sulfate by Postdilution On-Line Hemodiafiltration

Pablo Molina,Cristina Esteller,Mariola D Molina,Mercedes González-Moya,Julio Peiró,Belén Vizcaíno,María A Martínez-Gómez,Francisco Maduell,María García-Valdelvira

doi:10.3390/kidneydial1020015

Abstract

Dialytic clearance of p-cresyl sulfate (pCS) and other protein-bound toxins is limited by diffusive and convective therapies, and only a few studies have examined how to improve their removal by adsorptive membranes. This study tested the hypothesis that high-flux polymethylmethacrylate (PMMA) dialysis membranes with adsorptive capacity increase pCS removal compared to polysulfone membranes, in a postdilution on-line hemodiafiltration (OL-HDF) session. Thirty-five stable hemodialysis patients randomly completed a single study of 4 h OL-HDF with PMMA (BG2.1U, Toray®, Tokyo, Japan) and polysulfone (TS2.1, Toray®) membranes. The primary endpoint was serum pCS reduction ratios (RRs) obtained with each dialyzer. Secondary outcomes included RRs of other solutes such as β2-microglobulin, the convective volume obtained after each dialysis session, and the dialysis dose estimated by ionic dialysance (Kt) and urea kinetics (Kt/V). The RRs for pCS were higher with the PMMA membrane than those obtained with polysulfone membrane (88.9% vs. 58.9%; p < 0.001), whereas the β2-microglobulin RRs (67.5% vs. 81.0%; p < 0.001), Kt (60.2 ± 8.7 vs. 65.5 ± 9.4 L; p = 0.01), Kt/V (1.9 ± 0.4 vs. 2.0 ± 0.5; p = 0.03), and the convection volume (18.8 ± 2.8 vs. 30.3 ± 7.8 L/session; p < 0.001) were significantly higher with polysulfone membrane. In conclusion, pCS removal by OL-HDF was superior with high-flux PMMA membranes, appearing to be a good dialysis strategy for improving dialytic clearance of pCS, enabling an acceptable clearance of β2-microglobulin and small solutes.

Highlights

Chronic kidney disease (CKD) is characterized by the progressive accumulation of multiple chemical compounds that are normally excreted into the urine in healthy people [1,2,3,4,5]
Dialytic clearance of p-cresyl sulfate (pCS) and other protein-bound uremic toxins (PBUTs) is poor by diffusive treatment and limited by high-flux hemodialysis (HD) and on-line hemodiafiltration (OL-HDF), and only a few studies have examined how to improve their removal by other extracorporeal strategies [4,8,9,10,12]
As high-flux PS membranes with a restricted cut-off demonstrate low effectivity for the removal of PBUTs, we have studied whether the removal ratios of such uremic toxins may be improved by using adsorptive membranes such as PMMA

Summary

Introduction

Chronic kidney disease (CKD) is characterized by the progressive accumulation of multiple chemical compounds that are normally excreted into the urine in healthy people [1,2,3,4,5]. These chemical compounds are globally known under the name of uremic toxins and are conventionally classified into three groups based on their physicochemical properties [2]. Dialytic clearance of pCS and other PBUTs is poor by diffusive treatment and limited by high-flux hemodialysis (HD) and on-line hemodiafiltration (OL-HDF), and only a few studies have examined how to improve their removal by other extracorporeal strategies [4,8,9,10,12]

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