Effects of different doses in continuous veno-venous haemofiltration on outcomes of acute renal failure: a prospective randomised trial

Background Continuous veno-venous haemofiltration is increasingly used to t reat acute renal failure in critically ill patients, but a clear definition of an adequate treatment dose has not been established. We undertook a pro spective randomised study of the impact different ultrafiltration doses in continuous renal replacement therapy on survival. Methods We enrolled 425 patients, with a mean age of 61 years, in intensive care who had acute renal failure. Patients were randomly assigned ultrafil tration at 20 mL h(-1) kg(-1) (group 1, n=146), 35 mL h(-1) kg(-1) (group 2 , n=139), or 45 mL h(-1) kg(-1) (group 3, n=140). The primary endpoint was survival at 15 days after stopping haemofiltration. We also assessed recove ry of renal function and frequency of complications during treatment. Analy sis was by intention to treat. Results Survival in group 1 was;significantly lower than in groups 2 (p=0.0 007) and 3 (p=0.0013). Survival in groups 2 and 3 did not differ significan tly (p=0.87). Adjustment for possible confounding factors did not change th e pattern of differences among the groups. Survivors in all groups had lowe r concentrations of blood urea nitrogen before continuous haemofiltration w as started than non-survivors. 95%, 92%, and 90% of survivors in groups 1, 2, and 3, respectively, had full recovery of renal function. The frequency of complications was similarly low in all groups. Interpretation Mortality among these critically ill patients was high, but increase in the rate of ultrafiltration improved survival significantly. We recommend that ultrafiltration should be prescribed according to patient's bodyweight and should reach at least 35 mL h(-1) kg(-1).