The use of different buffers during continuous hemofiltration in critically ill patients with acute renal failure

Objective: To determine the impact of different hemofiltration (HF) replace ment fluids on the acid-base status and cardiovascular hemodynamics in pati ents with acute renal failure (ARF) and continuous veno-venous hemofiltrati on (CVVH). Design: Prospective, cohort study. Setting: Intensive Care Unit of the Heinrich Heine University Hospital, Dus seldorf, Germany. Subject and methods: One hundred and thirty-two critically ill patients wit h acute renal failure and continuous veno-venous HF were studied. Fifty-two patients were subjected to lactate-based (group 1), and 32 to acetate-base d hemofiltration (group 2)while 48 (group 3) were treated with bicarbonate- based buffer hemofiltration fluid. Fifty-seven had a septic, and 75 a cardi ovascular, origin of the ARE Creatinine, blood urea nitrogen (BUN), serum b icarbonate, arterial pH, lactate and Apache II scores were noted daily. Main results: The mean CVVH duration was 9.8 +/- 8.1 days, mortality was 65 %. No difference was present between the groups under investigation with re gard to the main clinical parameters. Lactate- and bicarbonate-based hemofi ltration led to significantly higher serum bicarbonate and arterial pH valu es as compared to the acetate-based hemofiltration. Serum bicarbonate value s at 48 h after the initiation of CVVH treatment were 25.7 +/- 3.8 mmol/l ( p < 0.001) in group 1, 20.6 +/- 3.1 mmol/l in group 2 and 23.3 +/- 3.9 mmol /l (p < 0.001) in group 3. While a lack of increase in serum bicarbonate an d arterial pH was correlated to poor prognosis in lactate- and bicarbonate- based hemofiltration, no such observation was made in acetate-based hemofil tration. Cardiovascular hemodynamics were superior in patients treated with lactate- and bicarbonate-based buffer solution as compared to those treate d with acetate-based buffer solution. Conclusions: The degree of correction of acidosis during hemofiltration was determined by patient outcome in patients treated with lactate- and bicarb onate-based buffer solutions, but not in patients receiving acetate-buffere d solution. Bicarbonate and lactate-based buffer solutions were found to be superior to acetate-based replacement fluid.