Blood volume-monitored regulation of ultrafiltration to decrease the dry weight in fluid-overloaded hemodialysis patients: a randomized controlled trial

Background: Because chronic fluid volume overload is associated with higher mortality, we tested whether blood-volume monitored regulation of ultrafiltration and dialysate conductivity (UCR) and/or regulation of ultrafiltration and temperature (UTR) would facilitate dry weight reduction, in comparison to conventional dialysis (CONV). Methods: We carried out a multicenter, 4-week, randomized controlled trial in hemodialysis patients = 15% above normal extracellular fluid volume (ECV), per bioimpedance spectroscopy, who were randomized 1: 1: 1. Applying UCR (Nikkiso), UTR (Fresenius) and CONV, initial dry weight was reduced rapidly to target. Dry weight reduction was attenuated and eventually stopped at the occurrence of dialysis complications. The primary outcome was defined as intra-and postdialytic complications. Secondary outcomes were magnitudes of dry weight and blood pressure reduction. Results: Of 244 patients assessed, N = 95 had volume overload = 15% above normal ECV. Fifty patients received the allocated interventions (N = 16 UCR, N = 18 UTR, N = 16 CONV) and completed the trial. The rate of complications was significantly lower in UTR compared to CONV (21 +/- 21% vs 34 +/- 20%, p = 0.022), and also compared to UCR (vs 39 +/- 27%, p = 0.028), but not statistically different between UCR and CONV (p = 0.93). Dry weight reduction was significantly higher in UTR compared to UCR (5.0 +/- 3.4% vs 2.0 +/- 2.7% body weight, p = 0.013), but not compared to CONV (vs 3.9 +/- 2.1% body weight, p = 0.31). Systolic blood pressure reduction throughout the intervention phase was 17 +/- 22 mmHg overall, but not significantly different between the three groups. Average maximum ultrafiltration rates were significantly higher in UTR than in UCR and CONV, at statistically similar dialysis times. Retrospective examination of randomly selected hemodialysis sessions in the UCR group identified technical mistakes in 36% of the dialysis sessions, despite considerable training efforts. Conclusions: Even in patients with volume overload, fluid removal was challenging. Despite the relative advantage of UTR, which must be interpreted with caution in view of the poor technical execution of UCR, this study renders clear that fluid removal must not be reinforced rapidly. Apprehension of this obstacle is imperative for future clinical and academic endeavors aimed at improving dialysis outcomes by correcting volume status.