Assessment of Hemodialysis Adequacy by Ionic Dialysance: Comparison to Standard Method of Urea Removal

Abstract

Background. The hemodialysis adequacy is one of the most important issues influencing the survival of patients on maintenance hemodialysis (HD). Assessment of measuring the delivered dialysis dose using clearance  time/volume (Kt/V) index requires multiple blood sampling. New methods for assessment of dialysis dose based on ionic dialysance (ID) have been suggested. Online conductivity monitoring (using sodium flux as a surrogate for urea) allows the repeated noninvasive measurement of Kt/V on each HD treatment. In this study we have compared this method with the standard method of estimating Kt/V. Methods. We studied 24 established HD patients over a 4 week time period. Patients were dialyzed using Fresenius 4008S dialysis monitors, equipped with modules to measure ID. Data were manually collected and analyzed using the appropriate statistical software. Urea removal (UR) was measured once a week by a two-pool calculation, estimating an eKt/V. Results. The Kt/V measured by ID highly correlated with the one derived from the measurement of the UR (r = 0.8959, p < 0.0001). The ID underestimated UR by the mean of 6%. The ID varied greatly within individual patients with a median of 1.29 ± 0.22. If the eKt/V ! 1.2 is considered adequate, 33% of the patients would have been inadequately dialyzed. The mean HD duration to achieve an adequate dialysis was 4 hours and 47 minutes with high interpatient variability. Conclusion. The ID seems to be an easily obtained measure of the delivered dialysis dose, correlating well with standard UR method. Substantial individual variations imply that repeated measures (ideally for all treatments) are necessary to obtain a real answer to the mean treatment dose being delivered to the patients.

Evaluation of hemodialysis adequacy using online Kt/V and single-pool variable-volume urea Kt/V

“…Application of such a method into practice worsens patients' satisfaction related to dialysis treatment and also does not eliminate a difference between SPVV urea Kt/V and online Kt/V, although it diminishes it to 1.5% [22]. A better correlation coefficient was also achieved in the study of Rački et al [23] when mean online Kt/V was related to equilibrated Kt/V (r = 0.8959). However, this correlation was much lower (r = 0.2071, P = 0.04) when the individual patient measurements were compared.…”

“…However, this correlation was much lower (r = 0.2071, P = 0.04) when the individual patient measurements were compared. The aforementioned data showed that online Kt/V underestimated urea removal by a mean of 6% [23].…”

Determination of Dialysis Dose: A Clinical Comparison of Methods

“…Apart from blood sample-based methods, alternative methods determining dialysis dose have been developed, mostly based on measurements of conductivity [4], [5] or of urea [6], recently also of ultraviolet absorbance in the spent dialysate [7]. …”

Use of ionic dialysance to calculate Kt/V in pediatric hemodialysis

“…Calculation of Kt/V using ionic dialysance without the need for blood samples was proposed as a bedside tool for frequent monitoring of HD, and was proven to be accurate in adults . It is widely used in adult patients on HD, but it has not been evaluated in children receiving HD.…”

“…The derived ionic dialysance then represents effective urea clearance from which Kt/V is calculated, allowing for Kt/V to be monitored at every treatment without blood sampling . This approach was found to correlate well with standard urea‐based method in adult patients on HD . Although widely used in adults, use of ionic dialysance has not been reported in pediatric HD.…”