Evaluation of a New Online Hemodiafiltration Mode with Automated Pressure Control of Convection

Abstract

Background: Postdilution hemodiafiltration (HDF) still remains the gold standard for solute removal, but with high hemoglobin levels transmembrane pressure (TMP) may reach high levels, reducing filter performance. We compared three online postdilution HDF treatments without TMP alarms for convective volume and plasma changes following treatment. Methods: Twelve patients were enrolled in a trial with three online postdilution HDF treatments. In the volume-controlled mode (VOLc), we set the exchanged volume to obtain a filtration fraction close to 25% without TMP alarms. In the pressure-controlled mode (TMPc), we set the TMP at 100 mm Hg. In the ULTRAc mode (TMP scan combined with TMPc), the dialysis machine automatically selects the TMP with a scan. All treatments were performed with an AK200 ULTRA-S system. Results: Even with hemoglobin levels >12 g/dl, we found a 57% rise in ultrafiltration rate in TMPc versus VOLc and a 92% rise in ULTRAc versus VOLc. Phosphates and myoglobin levels were significantly affected by treatment type. Conclusions: ULTRAc may be a useful tool to achieve an excellent purification performance without the constraints associated with the risk of hemoconcentration.

Achieving high convection volumes in postdilution online hemodiafiltration: a prospective multicenter study

“…Importantly, the high convection volumes were not associated with undesirable pressure changes. In this respect, it is of note that various manufacturers of dialysis equipment offer automatic optimization of the convection volume based on, for example, the transmembrane pressure [ 20 , 21 ]. Such software can automatically adjust the filtration fraction (but not treatment time or blood flow rate) during treatment.…”

Optimization of the convection volume in online post-dilution haemodiafiltration: practical and technical issues

“…In a recent report of the EUDIAL group [ 1 ], a FF of 20–25% was suggested. Nonetheless, values of up to 30% have been obtained using devices with automatic pressure-control [ 29 , 30 ]. Currently, it is unknown whether FF is a useful tool to maximize convection volumes in every day clinical practice.…”

Why should we focus on high-volume hemodiafiltration?

“…Accordingly, the European Dialysis Working Group recommended a filtration traction of 20% to 25% as appropriate in postdilution HDF [61]. Nevertheless, the use of a dialysis machine with an automatic pressure-control mode may extend the filtration fraction up to 30% [62]. The use of a dialysis machine with an automatic pressure-control mode can keep the transmembrane pressure within a range of 180 to 190 mmHg to prevent hemoconcentration, helping to obtain a high convection volume [49].…”