Effect of lowering dialysate sodium concentration on interdialytic weight gain and blood pressure in patients undergoing thrice-weekly in-center nocturnal hemodialysis: a quality improvement study

Abstract

Background: Patients on in-center nocturnal hemodialysis therapy typically experience higher interdialytic weight gain (IDWG) than patients on conventional hemodialysis therapy. We determined the safety and effects of decreasing dialysate sodium concentration on IDWG and blood pressure in patients on thrice-weekly in-center nocturnal hemodialysis therapy.

Study design: Quality improvement, pre-post intervention.

Settings & participants: 15 participants in a single facility.

Quality improvement plan: Participants underwent three 12-week treatment phases, each with different dialysate sodium concentrations, as follows: phase A, 140 mEq/L; phase B, 136 or 134 mEq/L; and phase A(+), 140 mEq/L. Participants were blinded to the exact timing of the intervention.

Outcomes: IDWG, IDWG/dry weight (IDWG%), and blood pressure.

Measurements: Outcome data were obtained during the last 2 weeks of each phase and compared with mixed models. The fraction of sessions with adverse events (eg, cramping and hypotension) also was reported.

Results: IDWG, IDWG%, and predialysis systolic blood pressure decreased significantly by 0.6 ± 0.6 kg, 0.6% ± 0.8%, and 8.3 ± 14.9 mm Hg, respectively, in phase B compared with phase A (P < 0.05 for all comparisons). No differences in predialysis diastolic and mean arterial or postdialysis blood pressures were found (P > 0.05 for all comparisons). The proportion of treatments with intradialytic hypotension was low and similar in each phase (P = 0.9). In phase B compared with phase A, predialysis plasma sodium concentration was unchanged (P > 0.05), whereas postdialysis plasma sodium concentration decreased by 3.7 ± 1.9 mEq/L (P < 0.05).

Limitations: Modest sample size.

Conclusion: Decreasing dialysate sodium concentrations in patients undergoing thrice-weekly in-center nocturnal hemodialysis resulted in a clinical and statistically significant decrease in IDWG, IDWG%, postdialysis plasma sodium concentration, and predialysis systolic blood pressure without increasing adverse events. Prolonged exposure to higher than required dialysate sodium concentrations may drive IDWG and counteract some of the purported benefits of "go-slow" (longer session length) hemodialysis.

Copyright © 2011 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.

Figures

Figure 1

Study design.

Figure 2

(A, B) Individual changes in intradialytic weight gain (IDWG) indexed by the estimated dry weight (IDWG%) and predialysis mean arterial pressure (MAP) throughout the different study phases. (A) Dashed lines represent participants (patients 15 and 7) with increased IDWG%, but decreased predialysis blood pressures in phase B. (B) Dashed lines represent participants (patients 11 and 13) who experienced higher predialysis blood pressures without increasing IDWG% in phase A.