**3.2.3 Interdialytic hypotension**

Of the five studies reporting interdialytic hypotensive events, two demonstrated more frequent hypotension on the lower sodium dialysate. The first found, 9% fewer dialysis sessions complicated by hypotension using higher dialysate sodium (Cybulsky et al., 1985). Of note, the dialysate sodium used in the "low sodium" cohort was 133mEq/L, the second lowest in all of the studies reviewed. However, given the yearlong duration of this study, the results cannot be dismissed lightly. The other study showing worsening BP stability during dialysis had an increased incident rate of approxamately 10% as well (Song, 2002). These studies highlight the limitations of reducing sodium indefinitely. There is a lower limit on decreasing serum osmolality before fluid shifts into the interstitium enough to cause hypotension. Two studies showed no change in intradialytic hypotension. One had the narrowest range of dialysate sodium (Thein et al., 2007) while the other had nearly the largest (see table 2 and Daugirdas et al., 1985). One study actually demonstrated better hemodyanamic stability on lower sodium dialysate highlighting the sometimes paradoxical effects of high sodium (de Paula et al., 2004): As hypertonic dialysate drives higher IDWG, ultrafiltration must increase in order to maintain steady dry weight. If IDWG becomes great enough, removing this excess fluid will put the patient at risk for intradialytic hypotension.
