Evaluation of a new online hemodiafiltration mode with automated pressure control of convection.
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.