Online conductivity monitoring of dialysis adequacy versus KtV derived from urea reduction ratio: A prospective study from a Saudi center

Abstract

Introduction.Adequate delivered dose of solute removal (as assessed by urea reduction and calculation of KtV) is an important determinant of clinical outcome in chronic hemodialysis (HD) patients. This requires both prescription of an adequate dose of HD and regular assessment that the delivered treatments are also adequate. Online conductivity monitoring (OCM) using sodium flux as a surrogate for urea allows for the repeated non-invasive measurement of KtV on each HD treatment.Methods.We prospectively studied 17 (9 males, 8 females) established chronic HD patients over an eight-week period (408 treatments). A pre- and post-dialyzer measurement of the conductivity is performed by two mutually independent temperature-compensated conductivity cells equipped with Fresenius 4008 S® dialysis machines. Urea reduction was measured once a week by a single-pool calculation using immediate post-treatment sampling. No changes were made to any of the dialysis prescriptions over the study period. Values of calculated KtV and simultaneously obtained online KtV were compared.Results.There was a statistically significant difference between calculated KtV and online KtV over the study period. The mean calculated KtV was 1.37 ± 0.09, and mean online KtV 1.02 ± 0.15 (p 0.000). Calculated KtV ≥ 1.2 was achieved in all our patients, while online KtV ≥ 1.2 was achieved in only 17.64. Yet there was moderate correlation between calculated KtV and online KtV (r2 0.48).Conclusions.Online conductivity monitoring (OCM) results underestimates dialysis efficiency compared to calculated KtV readings. This difference has to b considered when applying KtV to clinical practice. © Informa UK, Ltd.