Hemodialysis membrane surface chemistry as a barrier to lipopolysaccharide transfer

Abstract

During hemodialysis bacterial lipopolysaccharide (LPS) in contaminated dialysate solution may translocate across the hollow fiber membrane (HFM) to a patient's blood, resulting in fever and possible systemic shock. This study investigates LPS transfer across, and adsorption within, native and modified Fresenius Optiflux® F200NRe polysulfone (PS)/polyvinyl pyrrolidone (PVP) HFMs. Modifications include varied PVP content, addition of a PS‐poly(ethylene glycol) copolymer (PS‐PEG), and bleach sterilization. Under clinically relevant flow conditions LPS from >400 EU mL−1 spiked dialysate is not detected (<0.1 EU mL−1) in the lumens of native fibers, but is detected to varying degrees (0.2–15 EU mL−1) in the lumens of the modified fibers. Fluorescently labeled LPS predominantly adsorbs near the lumen of all membranes except the PS‐PEG containing membrane, where LPS localizes on the outer wall. Thus, addition of PS‐PEG may entrap LPS in the HFM spongy matrix, away from the blood‐contacting fiber lumen. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41550.

In vitro assessment of mixed matrix hemodialysis membrane for achieving endotoxin-free dialysate combined with high removal of uremic toxins from human plasma

“…Endotoxin was found in all the blood compartment samples, except for Optiflux F200NR (Fresenius) and for a thick-wall experimental membrane. Madsen et al [8] investigated the LPS transfer and adsorption of native and modified (varied PVP content, PS-PEG copolymer addition, bleach sterilization) Optiflux F200NR (Fresenius) HF. LPS was not detected in the lumen of the native fibers, but was detected to varying degrees in the lumen of modified fibers.…”

“…Indeed, for each patient treatment nearly 500 L of tap water are needed to obtain pure dialysis water, with two thirds of it discharged to the drain [5,6]. Moreover, even when ultra-pure water is obtained, inadequate design of the tubing system and improper machine maintenance might lead to water stagnation resulting in microbiological biofilm formation [2,[7][8][9]. The situation could be more dramatic in developing countries where the dialysis units have inadequate facilities for water purification [10].…”

“…As a consequence of bacterial growth and lysis in the water purification systems, bacterial pyrogens could be released and transferred into the patients' blood [5,7,[11][12][13]. A continued exposure to low levels of endotoxins contributes to the micro-inflammatory status of the hemodialysis patients leading to cardiovascular side effects, such as inflammatory amyloidosis and atherosclerosis, while exposure to higher level of endotoxins results in acute side effects as fever, hypotension, headache and muscular cramps [4,5,[7][8][9]11,14].…”

“…To minimize the risks of dialysis fluid contamination, additional filters can be inserted at the end of the purification cascade to avoid bacterial components, still present in the system, to reach the dialysis membrane [15][16][17]. Additionally, several sorbent systems have been studied for removing endotoxins from dialysis fluid and water solution, such as functionalized nanoparticles, plasma exchange, immobilized polymyxin B, poly-L-lysine, diethyl aminoethane, histamine, histidine and activated carbon [8,[18][19][20][21]. Besides, several studies have also investigated the ability of the dialysis filter itself to act as protective barrier for pyrogens during the therapy [14,22].…”

Amphiphilic Block Copolymer of Poly(dimethylsiloxane) and Methoxypolyethylene Glycols for High-Permeable Polysulfone Membrane Preparation

“…The polysulfone (PSf) membrane is widely used for its excellent chemical inertia, thermal stability, mechanical properties, and membrane forming ability . PSf membranes are frequently applied in gas separation, protein purification and fractionation, osmotic evaporation, hemodialysis, plasma separator, cell culture, and artificial liver. Nevertheless, the PSf membrane is vulnerable to fouling owing to its hydrophobic nature .…”