Ultrafiltration Rate in Prolonged Intermittent Kidney Replacement Therapy in Critically Ill Patients: A Randomized Controlled Trial

BACKGROUND: Fluid overload is a significant risk factor for mortality in critically ill patients with acute kidney injury. Ultrafiltration during kidney replacement therapy frequently produces hypotension. The optimal ultrafiltration rate in patients on vasopressor agents undergoing prolonged intermittent kidney replacement therapy (prolonged intermittent KRT) is unknown. AIM: This study was carried out to determine the optimal ultrafiltration rate among critically ill patients with acute kidney injury undergoing prolonged intermittent kidney replacement therapy. MATERIALS AND METHODS: We randomized patients to ultrafiltration rates of 2, 4 mL/kg/h, and a control (nephrologist's prescription) group. The mean arterial pressure, inotrope score, and vasopressor dependency index were measured before, at the mid-point, and after completing a session of prolonged intermittent KRT. Episodes of hypotension were also documented. The difference in hypotensive episodes and vasopressor dependency index between groups was the primary endpoint of the study. Exploratory analysis by stepwise logistic regression to determine the independent contribution of various factors to mortality was carried out. RESULTS: There was no difference between the groups at baseline. A significantly lower incidence of hypotension and premature session termination was found in the group randomized to a 4 mL/kg/h ultrafiltration rate compared with the groups prescribed 2 mL/kg/h and the control group (prescribed 2.65 mL/kg/h). The difference in pre and post mean arterial pressure and vasopressor dependency index was not significantly different between the 3 groups. Hypotension significantly increased the 30-day mortality risk and the length of stay (intensive care unit). CONCLUSION: In this study, we found that the group prescribed an ultrafiltration rate of 4 mL/kg/h had the lowest number of complications in critically-ill patients undergoing prolonged intermittent KRT for acute kidney injury.