How to relate toxin mass transfer to fluid dynamics in hemodialysis

Abstract

Hemodialysis (HD) therapy is of vital importance for patients with end stage renal disease (ESRD), when there is no donor organ available for transplantation to replace their malfunctioning kidneys. In contrast to healthy kidneys which work continuously and remove a broad range of toxins, during HD, patients’ blood is cleansed three times a week for 4 h and not all uremic toxins are removed. For achieving long-term and/or continuous therapies, including wearable artificial kidneys, one requires membranes with long-term blood compatibility and high fouling resistance. Most membranes currently used in the clinic are made by blending of hydrophobic polymers, such as polysulfone (PSu) or polyethersulfone (PES), with hydrophilic additives, such as polyvinylpyrrolidone (PVP). Studies however, have shown that PVP could leach out from the membranes, especially during prolonged therapy leading to membrane fouling and/or complications to patients.Here, we develop hollow fibers with no additive leaching, by blending PES with small amounts of SlipSkin™ (SS). The latter, a random copolymer consisting of N-vinylpyrrolidone (NVP) and N-butylmethacrylate (BMA), has very good blood compatibility. The developed fibers can achieve high removal of a range of uremic toxins (creatinine and protein-bound uremic toxins) combined with excellent fouling resistance.