Dialysate Sodium Levels, Ambulatory Aortic Blood Pressure, and Arterial Stiffness in Hemodialysis Patients

Background: Increased aortic blood pressure (BP) and arterial stiffness are associated with higher cardiovascular risk in hemodialysis. Previous works showed that lower dialysate sodium is associated with lower brachial-BP; data on aortic-BP and arterial stiffness are limited. This study aimed to investigate the effects of different dialysate sodium concentrations on 72-hour aortic-BP and arterial stiffness parameters in hemodialysis patients.

Methods: This analysis is part of a prospective, non-randomized interventional study. Twenty-five hemodialysis patients underwent a set of 3 periods of different dialysate sodium concentrations; 6 sessions with dialysate sodium of 137 mEq/l, followed consecutively by 6 sessions with 139 mEq/l and, finally, 6 sessions with 141 mEq/l. At the start of the sixth hemodialysis session on each sodium concentration, 72-hour ABPM (Mobil-O-Graph) was performed to evaluate aortic-BP and arterial stiffness indices during the overall 72-hour, different 24-hour, daytime, and nighttime periods.

Results: Mean 72-hour aortic systolic blood pressure (SBP)/diastolic blood pressure (DBP) were higher with increasing dialysate sodium concentrations (137 mEq/l: 114.2 ± 15.3/77.0 ± 11.8 mm Hg vs. 139 mEq/l: 115.4 ± 17.3/77.9 ± 14.0 mm Hg vs. 141 mEq/l: 120.5 ± 18.4/80.5 ± 14.7 mm Hg, P = 0.002/P = 0.057, respectively). Wave-reflection parameters (AIx, AIx(75), AP) were not significantly different between the 3 dialysate sodium concentrations. Ambulatory pulse wave velocity (PWV) was significantly higher with increasing dialysate sodium concentrations (137 mEq/l: 8.5 ± 1.7 m/s vs. 139 mEq/l: 8.6 ± 1.6 m/s vs. 141 mEq/l: 8.8 ± 1.6 m/s, P < 0.001). In generalized linear mixed models including 72-hour brachial SBP as a random covariate, the adjusted marginal means of 72-hour PWV were not significantly different between groups.

Conclusions: This study showed that higher dialysate sodium concentrations are associated with significant increases in ambulatory aortic BP and PWV. These findings further support the need for modification of dialysate sodium concentration in hemodialysis.