Audit of the effect of dialysate sodium concentration on inter-dialytic weight gains and blood pressure control in chronic haemodialysis patients.

Background/aims: Over the last three decades the standard dialysate sodium concentration has increased from 136 to 140 mmol/l (mEq/l) today. There has been great debate as to whether a reduction in dialysate sodium alone can lead to improved blood pressure control, and reduced inter-dialytic weight gain.

Methods: An audit was performed in 469 maintenance regular haemodialysis patients who dialysed in seven different centres under the care of one university medical school.

Results: Those centres which predominantly used a dialysate sodium of 140 mmol/l (mEq/l) had increased inter-dialytic weight gains, with more difficult blood pressure control, as not only did a greater percentage of patients require anti-hypertensive medication, but also more were prescribed multiple classes of anti-hypertensive agents. There was no difference in the frequency of symptomatic intra-dialytic hypotension.

Conclusions: A reduction in dialysate sodium was associated with lower inter-dialytic weight gains, without any additional intra-dialytic hypotensive episodes. Those patients in whom the difference between the time-averaged dialysate sodium concentration and the midweek pre-dialysis serum sodium was positive result had increased inter-dialytic weight gains, compared to those with a negative value. Reduced dialysate sodium alone was not effective in controlling blood pressure without additional proper dietary sodium restriction.