Introduction: Lowering dialysate sodium may improve volume and blood pressure control in maintenance hemodialysis patients.
Methods: We randomized 42 participants 2:1 to dialysate sodium 135 vs. 138 mEq/L for 6 months. This was followed by a 12 week extension in which sodium was increased to 140 mEq/L in low arm participants. The primary outcome was intradialytic hypotension (IDH). Secondary outcomes included dialysis disequilibrium symptoms, ER visits/hospitalizations, interdialytic weight gain, blood pressure (BP). Longitudinal changes across arms were analyzed using linear mixed regression.
Results: Treatment to dialysate sodium 135 vs. 138 mEq/L was not associated with a difference in a change in the rate of IDH (mean change (95%CI) 2.8 (0.8,9.5) vs. 2.7 (1.1, 6.2) events per 100 treatments per month; ratio of slopes 0.96(0.26,3.61) or ER visits/hospitalizations (7.3 (2.3, 12.4) vs. 6.7 (2.9, 10.6) events per 100 patient months; difference 0.6(-6.9,5.8). Symptom score was unchanged in the 135 mEq/L arm (0.7 (-1.4,2.7) and decreased in the 138 mEq/l arm (5.0,8.5,2.0); difference 6.0 (2.1,9.8)). Interdialytic weight gain declined in the 135 mEq/L arm and was unchanged in the 138 mEq/L arm,(-0.3(-0.5,0.0) vs. 0.3 (0.0, 0.6) kg over 6 months; difference (-0.6 (-0.1,-1.0) kg). In the extension phase, raising dialysate sodium from 135 to 140 mEq/L was associated with an increase in interdialytic weight gain (0.2 (0.1, 0.3) kg), predialysis BP (7.0 (4.8, 9.2)/ 3.9 (2.6, 5.1) mm Hg) and a reduction in IDH [OR 0.66 (0.45, 0.97)].
Conclusion: Use of a dialysate sodium of 135 as compared with 138 mEq/L was associated with a small reduction in interdialytic weight gain without impact on IDH or predialysis BP, but with an increase in symptoms. Raising dialysate sodium from 135 to 140mEq/L was associated with a reduction in IDH, a small increase in interdialytic weight gain and a marked increase in predialysis BP.
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