Elucidation of a fouling mechanism in hemofilters for continuous renal replacement therapy

Abstract

To elucidate the fouling mechanism of hemofilters, an aqueous ultrafiltration experiment was conducted. The hemofilters tested were AEF-10 (polysulfone membrane; henceforth abbreviated AEF), CH-1.3W (polymethylmethacrylate membrane; abbreviated CHW), and FLX-10GW (polyester polymer alloy membrane；abbreviated FLX). The albumin concentration of the aqueous test solution was 0.4g/dL and 4.0g/dL, the test solution flow rate (Q_B)was 100mL/min, and the total filtrate flow rate (Q_Ft) was held constant at 50mL/min. Sieving coefficient (s.c.) values for AEF hemofilters were initially high and then decreased with time at both albumin concentrations, but s.c. values for CHW and FLX hemofilters decreased with time as the albumin concentration increased from 0.4g/dL to 4.0g/dL. In addition, the filtrate flow rates at the inlet (Q_Fi) and outlet (Q_Fo) of the test solution were estimated from the material balance formula. With AEF hemofilters, Q_Fi and Q_Fo values were almost the same regardless of the albumin concentration. With CHW hemofilters, Q_Fi was higher than Q_Fo when the albumin concentration was 0.4g/dL, and the difference increased at concentrations of 4.0g/dL. With FLX hemofilters, Q_Fi and Q_Fo were almost the same when the albumin concentration was 0.4g/dL, but Q_Fi was higher when the concentration was 4.0g/dL. Therefore, fouling may occur at different sites depending on the hemofilter used, likely due to varying physicochemical features of the hemofilters.