Changes in Serum Bicarbonate Levels Caused by Acetate-Containing Bicarbonate-Buffered Hemodialysis Solution: An Observational Prospective Cohort Study

Abstract

Fresenius Medical Care's NaturaLyte dialysate has been associated with increased risk of sudden cardiac death by causing metabolic alkalosis from its acetate content based on retrospective data using pre-dialysis bicarbonate levels only. The study objective was to measure inter/intra-dialytic changes in serum bicarbonate and degree of alkalosis conferred by varying concentrations of NaturaLyte bicarbonate dialysate. Thirty-nine hemodialysis patients were divided into four groups based on prescribed bicarbonate dialysate concentrations; Group 1 (N = 9): 30-32 mEq/L, Group 2 (N = 5): 33-34 mEq/L, Group 3 (N = 10): 35-36 mEq/L, Group 4 (N = 15): 37-40 mEq/L. Serial (pre-dialysis, immediate post-dialysis, 2 h post-dialysis, and 68 h post-dialysis) bicarbonate levels were measured. Mean pre-dialysis serum bicarbonate levels (representing 44 h post-dialysis levels) in all four groups were not statistically different. Pre-dialysis and 68 h post-dialysis bicarbonate levels in each group were also not significantly different. However, immediate post-dialysis and 2 h post-dialysis bicarbonate levels were significantly increased in all four groups proportional to dialysate dose. There was statistically significant inter-group bicarbonate level difference (P < 0.05) except between the first and second (P = 0.43) and second and third (P = 0.07) groups in the immediate post-dialysis period. Similar results were obtained for the 2 h post-dialysis period. High bicarbonate dialysate causes large and rapid fluctuations in serum bicarbonate levels during the intra/inter-dialytic period, which returns to baseline within 44 to 68 h after dialysis. This refutes the necessity to correct pre-dialysis acidosis with high bicarbonate dialysate since rapid equilibration is likely to occur and unnecessarily exposes patients to large shifts in their acid base balance.

Keywords: Acetate; Acid-base balance; Bicarbonate; Hemodialysis; Metabolic alkalosis.