A pilot randomised controlled comparison of continuous veno-venous haemofiltration and extended daily dialysis with filtration: effect on small solutes and acid-base balance

Background and aims: Continuous veno-venous haemofiltration (CVVH) is an established treatment for acute renal failure (ARF). Recently, extended intermittent dialytic techniques have been proposed for the treatment of ARF. The aim of this study was to compare these two approaches. Setting: Intensive care unit of tertiary hospital. Subjects: Sixteen critically ill patients with ARF. Design: Randomised controlled trial. Intervention: We randomised sixteen patients to three consecutive days of treatment with either CVVH (8) or extended daily dialysis with filtration (EDDf) (8) and compared small-solute, electrolyte and acid-base control. Results: There was no significant difference between the two therapies for urea or creatinine levels over 3 days. Of 80 electrolyte measurements taken before treatment, 19 were abnormal. All values were corrected as a result of treatment, except for one patient in the CVVH group who developed hypophosphataemia (0.54 mmol/l) at 72 h. After 3 days of treatment, there was a mild but persistent metabolic acidosis in the EDDf group compared to the CVVH group (median bicarbonate: 20 mmol/l vs. 29 mmol/l: p=0.039; median base deficit: -4 mEq/l vs. -2.1 mEq/l, p=0.033). Conclusions: CVVH and EDDf as prescribed achieved similar control of urea, creatinine and electrolytes. Acidosis was better controlled with CVVH.