BackgroundCitrate is preferred over heparin as an anticoagulant in adult continuous renal replacement therapy (CRRT). However, its potential adverse effects and data on use in CRRT in infants and toddlers is limited. We conducted a prospective study on using citrate in CRRT in critically ill small children.MethodsChildren who underwent CRRT with the smallest filter in our PICU between November 2011 and November 2016 were included. Both heparin and citrate were applied according to a strict protocol. Our primary outcome was circuit survival time. Secondary outcomes were alkalosis, citrate toxicity, and number of red blood cell transfusions.ResultsHeparin was used in six patients (121 circuits, total CRRT time 3723 h). Citrate was used in 14 patients (105 circuits, total CRRT time 4530 h). Median circuit survival time with heparin was 21 h (IQR 14.5–27.5) compared to 45.2 h (IQR 37.5–52.8) with citrate (p < 0.001). Actual administered effluent dose compared to prescribed dose was 85% (IQR 69–98%) with heparin compared to 92% (IQR 88–98%) with citrate (p = 0.31). No patient treated with citrate developed citrate toxicity. No other differences in electrolytes were found between the two CRRT regimes. In the heparin group, a median of 6.5 units of red blood cells (IQR 1.5–23.8) were given during CRRT, compared to three in the citrate group (IQR 2.0–5.0, p = 0.12).ConclusionsUse of regional citrate significantly prolongs circuit survival time and thereby should increase CRRT efficiency when compared to heparin. In addition, citrate appears safe for CRRT in critically ill small children.