Determination of dialysis dose: a clinical comparison of methods

Guidelines recommend regular measurements of the delivered hemodialysis dose Kt/V. Nowadays, automatic non-invasive online measurements are available as alternatives to the conventional method with blood sampling, laboratory analysis, and calculation.

In a prospective clinical trial, three different methods determining dialysis dose were simultaneously applied: Kt/V(Dau) (conventional method with Daugirdas' formula), Kt/V(OCM) [online clearance measurement (OCM) with urea distribution volume V based on anthropometric estimate], and Kt/V(BCM) [OCM measurement with V measured by bioimpedance analysis (Body Composition Monitor)].

1,076 hemodialysis patients were analyzed. The dialysis dose was measured as Kt/V(Dau) = 1.74 ± 0.45, Kt/V(OCM) = 1.47 ± 0.34, and Kt/V(BCM) = 1.65 ± 0.42. The difference between Kt/V(OCM) and Kt/V(BCM) was due to the difference between anthropometric estimated V(Watson) and measured V(BCM). Compared to Kt/V(Dau), Kt/V(OCM) was 15% lower and Kt/V(BCM) 5% lower. Kt/V(Dau) was incidentally prone to falsely high values due to operative errors, whereas in these cases OCM-based measurements Kt/V(OCM) and Kt/V(BCM) delivered realistic values.

The automated OCM Kt/V(OCM) with anthropometric estimation of urea distribution volume was the easiest method to use, but Kt/V(BCM) with measured urea distribution volume was closer to the conventional method.