Ridel C et al. (2007) Ionic dialysance: a new valid parameter for quantification of dialysis efficiency in acute renal failure? Intensive Care Med 33: 460–465

For patients with acute renal failure (ARF) receiving intermittent hemodialysis (IHD), quantification of the 'dose' of dialysis delivered is problematic. Fractional dialysate sampling is the gold standard; however, this type of sampling is labor-intensive and, therefore, not routinely used. Dialysis dose is more frequently estimated on the basis of urea kinetics as Kt/V. This formula has only been validated in patients with chronic renal failure, and assumes a steady state and constant distribution of urea. The relevance of the Kt/V formula in ARF is, therefore, doubtful, as these assumed conditions are perturbed by hemodynamic instability and multiple interruptions to therapy. Ionic dialysance—calculated automatically by the dialysis unit in real time from the dialysate conductivity—is an alternative method of quantifying urea clearance. It is predicated on the similar transfer characteristics of ions and urea during IHD. Ridel et al. have demonstrated the applicability of this method to ARF in a population of 31 patients treated with IHD.

During each patient's initial IHD session, the researchers compared the dose of dialysis delivered as calculated by ionic dialysance, with the dose of dialysis delivered according to fractional dialysate sampling. A highly significant linear correlation was found between the two methods of dose determination (r = 0.96; P <0.01), and Bland–Altman analysis demonstrated very good limits of agreement (−2.21, 6.41). Dialysis efficiency had no effect on this association.