Effect of dialysate bicarbonate and sodium on blood pH in maintenance hemodialysis—A prospective study

Introduction: The validity of adjusting dialysate bicarbonate based on pre-hemodialysis (HD) serum bicarbonate is unclear. There are no studies of the impact of dialysate sodium on blood pH. Aims: To understand the impact of dialysate bicarbonate and sodium on blood pH. Methods: Two hundred arterialized blood samples were obtained on the third session of HD with four configurations of dialysate: sodium (140, 137 mEq/L) and bicarbonate (38, 32 mEq/L). Results: The correlation between pre-HD serum bicarbonate and pH was modest (r = 0.6). A lower dialysate sodium (p = 0.035) and a higher bicarbonate (p = 0.02) associated with a higher post-HD blood pH. The frequency of pre-HD blood pH of <7.4 and a post-HD blood pH of >7.5 did not differ for samples with serum bicarbonate <22, 22–26, or >26 mEq/L. Discussion/Conclusions: Adjusting dialysate buffer based on pre-HD serum bicarbonate is unnecessary. A higher bicarbonate and lower dialysate sodium associate with post-HD alkalemia.