Are all dialyzers compatible with the convective volumes suggested for postdilution online hemodiafiltration?

Introduction: The recent analysis of 4 randomized controlled trials has confirmed the lower mortality risk for postdilution online hemodiafiltration (OL-HDF) compared to hemodialysis, and above all for patients with the highest delivered body surface area standardized convective volume (CV/BSA >23 L/1.73 m²/session). Since the impact of the dialyzers used in these trials has never been studied, we retrospectively analyzed clinical tests carried out with 19 commonly used dialyzers. The aim was to provide information on their performances and behavior to aid in an objective choice for therapies associated with OL-HDF.

Methods: "Efficiency" was evaluated by measuring the reduction ratio of beta-2 microglobulin (RRß2M) and myoglobin (RRmyo) for a CV/BSA between 0 and 30 L, extrapolating them at CV/BSA = 23 L. "Safety" was defined by the safe CV (CVsafe), corresponding to the CV/BSA above which albumin loss is >5 g/session.

Results: With CV/BSA = 23 L, all the dialyzers ensure an optimal ß2M extraction (RRß2M: 76%-84.5%). For myoglobin, efficiency disparities are bigger (RRmyo: 40%-85%). Above all, 4/19 dialyzers lose more than 5 g albumin and should not be used under these conditions.

Conclusions: It is recommended to prescribe dialyzers that are above all safe. Moreover, if one considers that the removal of middle molecule solutes prevails over the CV necessary for their transmembrane transport, some dialyzers that are more efficient with CV/BSA <23 L than others with CV/BSA >= 23 L might then be prescribed when the conditions do not permit the suggested CV/BSA goal to be achieved.