Comparison of a lactate-versus acetate-based hemofiltration replacement fluid in patients with acute renal failure

The objective of the study was to determine the impact of a lactate- and an acetate-based hemofiltration replacement fluid (HF) on the acid-base status in patients with acute renal failure (ARF) and continuous venovenous hemofiltration (CVVH). The prospective, cohort study was carried out in the intensive care unit of the Heinrich-Heine University Hospital, Dusseldorf, FRG. Subjects were 84 critically ill patients with ARF and CVVH. Fifty-two patients were subjected to lactate-based (group 1) and 32 to acetate-based hemofiltration (group 2). Thirty-eight patients had a septic, 46 a cardiovascular origin of the ARF. Creatinine, BUN, serum bicarbonate, arterial pH, lactate and APACHE II score were noted daily. Mean CVVH duration was 9.8 +/- 8.1 days; mortality was 65%. The groups did not differ with regard to the main clinical parameters. Lacate-based hemofiltration led to significantly higher serum bicarbonate and arterial pH values as compared to the acetate-based hemofiltration. Baseline serum bicarbonate values were 23.3 +/- 8.3 mmol/L in group 1 and 21.6 +/- 4.3 mmol/L in group 2 (NS); values at 48 h after initiating CVVH treatment were 25.7 +/- 3.8 mmol/L and 20.6 +/- 3.1 mmol/L, respectively (p < 0.001). Arterial pH prior to CVVH treatment was 7.36 +/- 0.1 in group 1 and 7.34 +/- 0.1 in group 2 (NS), and 7.43 +/- 0.07 versus 7.37 +/- 0.06 (p < 0.001) on day 2. These findings were maintained throughout therapy. While a lack of increase in serum bicarbonate and arterial pH was correlated to a poor prognosis in lactate-based hemofiltration, no such observation could be made in acetate-based hemofiltration. Septic patients did not differ in their acid-base status from nonseptic patients. Lactic acidosis occurred in 8 septic patients irrespective of the substitution fluid. All 8 patients died. There was a significant increase in HCO3 and arterial pH values in lactate-based as compared to acetate-based HF.