Dialyzer fiber bundle volume during Hemodialysis using large-surface dialyzers

Our aim was to measure and compare fiber bundle volume (FBV) of three large-surface dialyzers during chronic hemodialysis; FBV was evaluated inpatients without heparin (n = 6),with tight heparinization (n = 6), and with large doses of heparin (n = 6). Each patient was treated consecutively with three dialyzers: Nephral ST500, Tricea210, and Optiflux200NR. FBV was measured hourly by ultrasound dilution in 54 sessions (n = 270). For all patients (without heparin, tight heparin, and large heparin doses) FBV did not vary significantly from 0 to 4 hours for the three types of dialyzers. There was no significant difference in aspect of filters/tubings at the end of dialysis and the presence of clots in the circuit assessed hourly. In addition, 6 other patients on hemodialysis without heparin were treated with Nephral ST500 alternatively with and without saline flushes, thus, 12 more sessions were monitored hourly for FBV (n = 60). There was no change in FBV from 0 to 4 hours between the two approaches, and the appearance of dialyzers/tubings was similar. We conclude that the FBV of large-surface dialyzers is well maintained during 4-hour chronic high-flux hemodialysis and that the loss of dialyzer surface does not explain the difference between prescribed and delivered dialysis dose in such circumstances. The membrane AN69ST does not appear more thrombogenic nor require saline flushes for heparin-free hemodialysis.