Response Options to Blood Volume Monitoring in Fluid Overloaded Hemodialysis Patients (BVM-Reg)

Background: Data generated with the body composition monitor (BCM, Fresenius) show based on bioimpedance technology, that chronic fluid overload in hemodialysis patients is associated with poor survival. However, removing excess fluid by lowering dry weight can be accompanied by intradialytic and postdialytic complications. Here, we aim at testing the hypothesis that, in comparison to conventional hemodialysis, blood-volume monitored regulation of ultrafiltration and dialysate conductivity (UCR) and/or regulation of ultrafiltration and temperature (UTR) will decrease complications when ultrafiltration volumes are systematically increased in fluid overloaded hemodialysis patients.

Methods/Design: BCM-measurements yield results on fluid overload (in liters), relative to extracellular water (ECW). In this prospective, multicenter, triple-arm, parallel group, cross-over, randomized, controlled clinical trial, we use BCM-measurements, routinely introduced in our 3 maintenance hemodialysis centers shortly prior to the start of the study, to recruit 60 hemodialysis patients with fluid overload (defined as ≥15% ECW). Patients are randomized 1:1:1 into UCR, UTR and conventional hemodialysis groups. BCM-determined, 'final' dry weight is set as -7% ECW postdialysis, and reached by reducing the previous dry weight, in steps of 0.1 kg per 10 kg body weight, during 12 hemodialysis sessions (one study phase). In case of intradialytic complications, dry weight reduction is decreased, according to a pre-specified algorithm. A comparison of intra- and postdialytic complications among study groups constitutes the primary endpoint. In addition, we will assess relative weight reduction, changes in residual renal function, quality of life measures, and predialysis levels of various laboratory parameters including C-reactive protein, troponin T, and N-terminal pro-B-type natriuretic peptide, before and after the first study phase (secondary outcome parameters).

Discussion: Patients are not requested to revert to their initial degree of fluid overload after each study phase, Therefore, the cross-over design of the present study merely serves the purpose of secondary end-point evaluation, for example to determine patient choice of treatment modality. Previous studies on blood volume monitoring have yielded inconsistent results. Since we include only patients with BCM-determined fluid overload, we expect a benefit for all study participants, due to strict fluid management which decreases the mortality risk of hemodialysis patients.