The effect of sodium exchange and dialytic biochemical parameters on blood pressure, arterial stiffness, and endothelial functions in patients with peritoneal dialysis

OBJECTIVE

This study aimed to investigate the relationship between fluid and sodium excretion and blood pressure, echocardiographic parameters, and arterial stiffness in peritoneal dialysis (PD) patients and to evaluate the effect of sodium excretion on patients' survival.

METHOD

This study was conducted as a single-centered, prospective study in the Department of Nephrology in Erciyes University. The patients included in the study were followed up for 3 years. Seventy PD patients were included in the study. We recorded demographic characteristics, biochemical parameters, urine and peritoneal ultrafiltration volumes, peritoneal equalization tests, ambulatory blood pressure measurements, and echocardiographic measurements. We measured the amount of total sodium excretion of the patients and arterial stiffness using pulse wave velocity (PWV). Patients were divided into two groups based on the amount of total sodium excretion: low group and high group. We compared these groups in terms of cardiac and biochemical parameters.

RESULTS

When demographic data and biochemical values were compared, there was no significant difference between the two groups. NT-proBNP level, systolic blood pressure, and mean arterial pressure were significantly higher in the low group (p: 0.02, p: 0.031, p: 0.05, respectively). Net ultrafiltration was significantly higher in the high group (p: 0.03), was also found to be high in patients with high sodium excretion (p: 0.001). Negative correlations were found between sodium excretion and net ultrafiltration, NT-Pro BNP, and PWV. At the end of the 3-year follow-up, the survival rate was shorter and the mortality rate was higher in the low group (p: 0.042).

DISCUSSION AND CONCLUSION

Fluid status in PD patients can affect arterial stiffness both directly and through hypertension. Correction of hypervolemia has the potential to not only prevent hypertension and left ventricular hypertrophy, but also to improve arterial stiffness, a well-known cardiovascular risk factor. The mortality rate was higher in PD patients with low total sodium excretion. Therefore, these patients should be followed more closely to ensure volume control.

Prognostic Significance of Serum Indoxyl Sulfate and Albumin for Patients with Cardiovascular Disease

The progression of renal dysfunction reduces serum albumin and deteriorates the binding capacity of protein-bound uremic toxins. We evaluated the prognostic implications of serum indoxyl sulfate (IS) and albumin levels in patients with cardiovascular disease.We prospectively enrolled 351 consecutive patients undergoing percutaneous revascularization for coronary artery disease or peripheral artery disease. The primary endpoint was all-cause mortality. Patients were assigned to four groups according to the median levels of serum IS (0.1 mg/dL) and albumin (3.9 g/dL).During the median follow-up time of 575 days, 16 patients died. The IS level was significantly higher in nonsurvivors (0.33 versus 0.85 mg/dL, P < 0.05). On the Kaplan-Meier curve, the high IS/low albumin group presented the highest mortality rate (log-rank test, P < 0.01). Cox proportional hazard analysis revealed that high IS/low albumin (hazard ratio (HR): 5.33; 95% confidence interval (CI): 1.71-16.5; P < 0.01), diastolic pressure (HR: 0.94; 95% CI: 0.91-0.98; P < 0.01), prior stroke (HR: 4.54; 95% CI: 1.33-15.4; P = 0.01), and left ventricular ejection fraction (LVEF) (HR: 0.92; 95% CI: 0.88-0.96; P < 0.001) were associated with increased mortality. Furthermore, the combination of IS and albumin levels significantly conferred an additive value to LVEF for predicting mortality (C-statistic: 0.69 versus 0.80; P < 0.001; net reclassification improvement: 0.83; P < 0.001; integrated discrimination improvement: 0.02; P = 0.02).A lower albumin level adds potentiating effects on IS as a prognostic factor for cardiovascular disease.