Does the relationship between measured and prescribed dialysate sodium matter in the nephrology community?

Conductivity variations and changes in serum sodium concentration during dialysis related to monitor switching

INTRODUCTION

The sodium gradient during hemodialysis sessions is one of the key factors in sodium balance in patients with dialysis-dependent chronic kidney disease; however, until the appearance of the new monitors with sodium modules, the differences between prescribed and measured sodium have been understudied. The present study aimed to compare the impact on the measured conductivity and the initial and final plasma sodium after changing the 5008 Cordiax to the new 6008 Cordiax monitor.

MATERIAL AND METHODS

106 patients on hemodialysis were included. Each patient underwent 2 dialysis sessions in which only the monitor was varied. The variables collected were dialysate, sodium and bicarbonate prescribed, real conductivity, initial and final plasma sodium measured, and the calculated sodium gradient (ΔPNa).

RESULTS

The change of dialysis monitor showed small but statistically significant differences in the initial (138.14mmol/L with 5008 vs. 138.81mmol/L with 6008) and final plasma sodium (139.58mmol/L vs. 140.97mmol/L), as well as in the actual conductivity obtained (13.97 vs. 14.1mS/cm). The ΔPNa also increased significantly.

CONCLUSION

The change from 5008 to 6008 monitor is associated with increased conductivity, leading the patient to end the sessions with higher plasma sodium and ΔPNa. Knowing and confirming this change will allow us to individualize the sodium prescription and avoid possible undesirable effects. It could be the preliminary study to explore the new sodium biosensor incorporated into the new generation of monitors.

Practical implementation and clinical benefits of the new automated dialysate sodium control biosensor

Background

A key feature of dialysis treatment is the prescription of dialysate sodium (Na). This study aimed to describe the practical implementation of a new automated dialysate Na control biosensor and to assess its tolerance and the beneficial clinical effects of isonatraemic dialysis.

Methods

A prospective study was carried out in 86 patients who, along with their usual parameters, received the following five consecutive phases of treatment for 3 weeks each: phase 0: baseline 5008 machine; phases 1 and 2: 6008 machine without activation of the Na control biosensor and the same fixed individualized Na dialysate prescription or adjusted to obtain similar conductivity to phase 0; phases 3 and 4: activated Na control to isonatraemic dialysis (Na dialysate margins 135-141 or 134-142 mmol/L).

Results

When the Na control was activated, the few episodes of cramps or hypotension disappeared when the lower dialysate Na margin was increased by 1 or 2 mmol/L. The activated Na control module showed significant differences compared with baseline and the non-activated Na module in final serum Na values, diffusive Na balance, and changes in pre- to postdialysis plasma Na values. The mean predialysis systolic blood pressure value was significantly lower in phase 4 than in phase 1. There were no significant differences in total Na balance in the four 6008 phases evaluated.

Conclusions

The implementation of the automated dialysate Na control module is a useful new tool, which reduced the diffusive load of Na with good tolerance. The module had the advantages of reducing thirst, interdialytic weight gain and intradialytic plasma Na changes.