Weight gains and increased blood pressure in outpatient hemodialysis patients due to change in acid dialysate concentrate supplier.

INTRODUCTION: Sodium balance during hemodialysis is predominantly achieved by ultrafiltration. The additional effect of diffusional sodium losses and gains remains unclear. We recently changed our dialysate acid concentrate supplier, and although both concentrates were instructed to be diluted 1:44, we audited the practical effects of this change.
METHODS: Review of electronic dialysis and laboratory records of patients attending a satellite dialysis center.
RESULTS: 91 adult hemodialysis patients, mean age 61.4 ± 1.7 years, 65% male, 52% diabetic, median dialysate sodium machine setting at 137 mmol/l (137-138), following change in acid dialysate patients dialyzed against a mean measured dialysate sodium of 4.8 (95%cCL 3.6-6.1) mmol/l higher than setting. After six weeks, pre-dialysis weight increased from 75.5 ± 1.9 kg to 76.6 ± 1.9 kg, p<0.001, with increased mean weight loss on dialysis from 2.38 ± 0.1% to 3.28 ± 0.13%, p<0.001, and increase in pre-dialysis mean arterial blood pressure from 91.2 ± 1.5 mmHg to 95.4 ± 1.5 mmHg, p<0.001. Post-dialysis serum sodium increased from 0 (-3 to +3) mmol/l to +3 (1 to 5.5) mmol/l compared to pre-dialysis value, p<0.001. Monthly symptomatic episodes of intradialytic hypotension fell from 69 to 46. After correcting the dialysate sodium setting, blood pressure and weight gains resolved over 4 weeks.
CONCLUSIONS: Changing dialysate acid concentrates, both labeled 1:44 dilution, led to the delivery of a higher dialysate sodium, resulting in weight gains, increased pre-dialysis blood pressure, but less symptomatic intradialytic hypotension. Following readjustment of volumetric dialysate mixing, excess weight gains and increased blood pressure resolved over 4 weeks, highlighting the importance of checking the delivered dialysate sodium following a change in dialysate acid concentrate.