Original Article Associations of a facility level decrease in dialysate sodium concentration with blood pressure and interdialytic weight gain

Background. Dialysate [Naþ] is often overlooked as a contributor to hypertension in patients on haemo-dialysis (HD). We report observational experience with a facility level decrease in dialysate [Naþ] from 141mmol/l to 138mmol/l, in the absence of concurrent change with respect to dietary sodium regulation. Methods. The sample comprised all patients (n 52) dialysing at a single HD facility over an 8-month period flanking the change in dialysate [Naþ]. Outcomes included repeated observations of blood pressure (BP), interdialytic weight gain (IDWG), pre-dialysis plasma [Naþ] and adverse events. Predictors other than dialysate [Naþ] included patient demographics, clinical characteristics and number of antihypertensive medications. The study used a long-itudinal unbalanced panel design, and hierarchical linear and Poisson mixed models. Results. In multivariate analyses, the change in dialysate [Naþ] was associated with a statistically significant small to medium-sized decrease in pre-and post-dialysis systolic and diastolic BP, pre-dialysis plasma [Naþ], but not IDWG. Change was greatest in the patient tertile with the highest initial BP. There was no change in the frequency of adverse events. Modelling dialysate [Naþ] exposure as the diffusion gradient from dialysate to blood water did not improve the strength of associations. Conclusions. A facility level decrease in dialysate [Naþ] from 141mmol/l to 138mmol/l appears to be safe and well tolerated, and a useful means of improving BP control. The lack of change in IDWG probably reflects lack of dietary salt restriction, and but does raise the issue of volume-independent effects of sodium exposure on BP