Effects of High Blood Flow and High Pre-Dilution Replacement Fluid Rates on Small Solute Clearances in Hemofiltration

Background/Aims: In pre-dilution hemofiltration (HF), solute clearance is less than the HF rate. While the amount of this loss is predictable, it has not been validated in high-volume HF associated with high blood flow rates. Methods: Using isovolemic pre-dilution HF, we studied small solute clearances using combinations of blood flow (Q(B); 150, 250, 350, 450 ml/min) and replacement fluid (RF) flow (Q(RF); 2, 4, 6 l/h) to determine clearance losses we entitled 'measured efficiency' (E-M). E-M was compared to predicted efficiency (E-P) = (Q(B)/Q(B) + Q(RF)). Results: Pre-dilution produced E-M values of 61-93%. Increases in Q(B) for any Q(RF) and decreases in Q(RF) for any Q(B) increased E-M over a wide range of Q(B) and Q(RF). E-P was equivalent to E-M. Conclusion: In high-volume pre-dilution HF, E-P can be used to determine E-M across a broad range of Q(B) and Q(RF) values. Higher Q(RF) requires higher Q(B) to minimize the attenuating effects of pre-dilution on clearance. Copyright (C) 2011 S. Karger AG, Basel