Experimental analysis of dialysate conductivity as a function of sodium content

This thesis investigates the relationship between sodium concentration and conductivity of the dialysate used in hemodialysis treatment. In hemodialysis, the composition of the dialysate is crucial, particularly the sodium concentration, which regulates plasma osmolarity and fluid balance. Sodium levels are not measured directly by dialysis machines but are inferred from the dialysate conductivity, which depends on the total ionic concentration. Two models were developed to describe this relationship: the first normalized the correction factor by the total ionic concentration, while the second related it to the square root of the ionic concentration. Experimental measurements were performed on dialysate prepared with K3 and K2.5 acid concentrates and bicarbonate solutions. They showed approximately linear trends with mild exponential behaviors relating sodium concentration to conductivity and mild behavior relating conductivity to sodium concentration. No significant difference exists between the two dialysate types. From the comparison between the theoretical and experimental models, results demonstrated that the first theoretical model was unable to accurately predict the relationship under investigation; whereas the second model provided reliable predictions for sodium concentration within the range of interest, except near the upper limit. These findings open the way for further work focusing on repeating the experimental measurements under the operational condition of the dialysis machine, as well as validating the results using different measurement instruments to ensure accuracy and reproducibility.