Efficiency of high permeable membranes in hemodiafiltration in children: an optimal method of purification.

Hemodiafiltration (HDF) combines hemodialysis (HD) and hemofiltration (HF) and so allows an optimal purification by combining diffusive process (low molecular weight compounds) with convective mass transport (middle molecular weight compounds). A high permeable membrane is analysed (clearance, extraction coefficient, sieving coefficient) at 30 min and 150 min session time in HD, HF and HDF conditions. There is not a better elimination of urea in HDF versus HD while HDF allows an optimal elimination of uremic toxins in the range of low and middle molecular weight compounds. A high (optimal?) filtrate flow, with a minimal risk, is given by the formula: QUF = 1/3 QB. Sieving coefficient in HF condition of the other membranes generally employed in pediatric HDF demonstrated a great variability for the cut off.