Poly(N-vinyl-2-pyrrolidone) elution from polysulfone dialysis membranes by varying solvent and wall shear stress

Abstract

Some dialysis patients are treated with post-hemodiafiltration (HDF); the blood viscosity of the patients who undergo post-HDF is higher than that of the patients who undergo conventional hemodialysis. This study aims to evaluate poly(N-vinyl-2-pyrrolidone) (PVP) elution from PSf dialysis membranes by varying solvents and high wall shear stress caused by blood viscosity. We tested three commercial membranes: APS-15SA (Asahi Kasei Kuraray), CX-1.6U (Toray) and FX140 (Fresenius). Dialysate and blood sides of the dialyzers were primed with reverse osmosis (RO) water and saline. RO water, saline and dextran solution (2.9 and 5.8 mPa s) were circulated in the blood side. The amount of eluted PVP was determined by 0.02 N iodometry. The hardness and adsorption force of human serum albumin (HSA) on the membrane surfaces were measured by the atomic force microscope. When wall shear stress was increased using dextran, the amount of PVP eluted by the 2.9 mPa s solution equaled that eluted by the 5.8 mPa s solution with APS-15SA and CX-1.6U sterilized by gamma rays. The amount of PVP eluted by the 5.8 mPa s solution was higher than that eluted by the 2.9 mPa s solution with FX140 sterilized by autoclaving. The wall shear stress increased the PVP elution from the surface, hardness and adsorption force of HSA. Sufficient gamma-ray irradiation is effective in decreasing PVP elution.

Influence of Sterilization and Storage Period on Elution of Polyvinylpyrrolidone from Wet-Type Polysulfone Membrane Dialyzers

“…16,20 However, the amount of PVP eluted from the APS dialyzer increased along with the storage period in this study ( Figure 5B). The reason for this increase of PVP elution may have been oxidative decomposition of cross-linked PVP during prolonged storage.…”

“…Because shear stress due to circulation of blood in clinical HD is greater than in this study, elution of PVP is likely to exceed these experimental findings. 16 Thus, it is a concern that elution of PVP could affect the safety of dialysis patients and the biocompatibility of the dialyzer.…”

“…[16][17][18] However, differences of the PVP content between different commercially available PSu membrane dialyzers were not assessed in previous studies, because the amount of PVP added to each commercial dialyzer is a trade secret.…”

“…10,[13][14][15] However, PVP is easily eluted from the PSu membrane because it is water soluble. 9,16 Polyvinylpyrrolidone is also removed from the PSu membrane surface by shear stress between circulating fluids and the membrane. 16 Elution of PVP affects the biocompatibility of the PSu membrane dialyzer during HD therapy, 17 and all of the eluted PVP enters the HD patient.…”

“…9,16 Polyvinylpyrrolidone is also removed from the PSu membrane surface by shear stress between circulating fluids and the membrane. 16 Elution of PVP affects the biocompatibility of the PSu membrane dialyzer during HD therapy, 17 and all of the eluted PVP enters the HD patient. Therefore, elution of PVP from PSu membranes is one of the important issues with respect to both biocompatibility of the dialyzer and patient safety.…”