Ionic dialysance: a new valid parameter for quantification of dialysis efficiency in acute renal failure?

Objective: Several studies have reported a close relationship between an increased dose of dialysis and survival in patients treated for acute renal failure. Unfortunately, the quantification of dialysis in critically ill patients based on the urea nitrogen formula Kt/V is not applicable. Ionic dialysance is a new parameter calculated in real time from the dialysate conductivity and correlated with the effective urea clearance in chronic hemodialysis patients. The aim of our study was to evaluate ionic dialysance in the quantification of dialysis in critically ill patients with acute renal failure. Design: Prospective open-label study. Setting: An 18-bed medical intensive care unit. Patients: Thirty-one patients with multiple organ dysfunction syndrome and acute renal failure requiring intermittent hemodialysis were included. Measurements: Using the first dialysis session of each patient, we compared the delivered dose of dialysis based on ionic dialysance measurement (Kt(ID)) with the well-accepted gold standard method based on fractional dialysate sampling (Kt(dialysate)). The data were analyzed using linear regression and Bland-Altman analysis. Results: Thirty-one intermittent hemodialysis sessions were performed in 31 critically ill patients (mean age 58 +/- 12 years, SAPS II score 56 +/- 10). We found a close correlation between Ktdialysate and KtID (Ktdialysate = 36.3 +/- 11.41; KtID = 38.4 +/- 11.8; r = 0.96) with excellent limits of agreement (-2.21; 6.41). Conclusion: The feasibility of dialysis quantification based on ionic dialysance in the critically ill patient is good. This method is a simple and accurate tool for the determination of dialysis dose in critically ill patients.