Do bicarbonate-based solutions for continuous renal replacement therapy offer better control of metabolic acidosis...

Evidence that bicarbonate haemofiltration and dialysate fluids are superior to lactate in patients with acute kidney injury treated by continuous renal replacement therapy (CRRT) remains controversial.

We prospectively audited acid-base during the first 48 h of CRRT in 62 patients, using bicarbonate and lactate fluids.

Baseline lactate was greater in the bicarbonate group (4.76 ± 0.77 vs. 2.92 ± 0.5 mmol/l, p < 0.01), but pH, bicarbonate, chloride and base excess were similar. Lactate fell significantly in the bicarbonate group to 2.88 ± 0.3 mmol/l at 24 h and 2.39 ± 0.2 mmol/l at 48 h, but not in the lactate group. Base excess improved more with bicarbonate, median increase in the first 24 h was 51.6% (29.1-96.9) versus 18.5% (-5 to 55) with lactate and 74.2% (38.5-123) versus 36.1% (-3.6 to 68), p < 0.05 at 48 h. However, there were no significant differences in bicarbonate, chloride, pH, blood pressure and vasopressor requirements. 13.3% of patients were switched from lactate to bicarbonate fluids due to failure to correct acidosis. Subgroup analysis of 19 patients with liver failure showed similar results.

Bicarbonate fluids led to a more rapid fall in lactate and greater improvement in base excess during CRRT, but not overall control of acidosis.