Effect of continuous venovenous hemofiltration with dialysis on lactate clearance in critically ill patients

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Abstract
Objective To evaluate the effect of continuous venovenous hemofiltration with dialysis on lactate elimination by critically ill patients. Design Prospective, clinical study. Setting Surgical intensive care unit of a university hospital. Patients Ten critically ill patients with acute renal failure and stable blood lactate concentrations. Interventions Two-stage investigation: a) measurement of lactate concentrations in samples of serum and ultradiafiltrate from patients receiving continuous venovenous hemofiltration with dialysis to calculate lactate clearance by the hemofilter; b) evaluation of total plasma lactate clearance by infusing sodium L-lactate (1 mmol/kg of body weight) over 15 mins. Measurements and Main Results Arterial lactate concentration was determined before, during, and after the infusion. Lactate elimination variables were calculated from the plasma curve using model-independent and model-dependent estimates (by software). At the end of the infusion, median blood lactate concentration increased from 1.4 mmol/L (range 0.8 to 2.6) to 4.8 mmol/L (range 2.4 to 5.7) and returned to 1.6 mmol/L (range 0.9 to 3.4) 60 mins later. The median total plasma lactate clearance was 1379 mL/min (range 753.7 to 1880.7) and the median filter lactate clearance was 24.2 mL/min (range 7.1 to 35.6). Thus, filter lactate clearance accounted for <3% of total lactate clearance. Conclusions Continuous venovenous hemofiltration with dialysis cannot mask lactate overproduction, and its blood concentration remains a reliable marker of tissue oxygenation in patients receiving this renal replacement technique. (Crit Care Med 1997; 25:58-62)