CRITICAL ANALYSIS OF FORMULAS FOR ESTIMATING BACKFILTRATION IN HEMODIALYSIS

The advent of high-flux dialyzers introduced the phenomenon of backfil tration as a regular occurrence in hemodialysis. Methods for calculati ng an estimate of backfiltration are described in detail, including an examination of the response of backfiltration to changes in applied p ressure. A simple expression for the prediction of backfiltration as a function of net ultrafiltration is presented. Methods for estimating backfiltration have been published previously, but were based on incor rect assumptions; the errors present in those papers are highlighted a nd discussed here.