ObjectiveTo investigate the timing and efficacy of continuous renal replacement therapy (CRRT) in neonatal acute kidney injury (AKI).MethodsNineteen AKI neonates treated with CRRT were enrolled during hospitalization in the Department of Neonatology of the Children's Hospital of Shanghai from June 2011 to June 2018. Their clinical data were retrospectively analyzed. According to their baseline renal function, these neonates were divided into two groups using an improved RIFLE (Risk, Injury, Failure, Loss and End-stage renal disease) standard: AKI stage 1-2 group and AKI stage 3 group. CRRT included continuous veno-venous hemodiafiltration (CVVHDF) and plasma exchange (PE). Several parameters included blood pressure (BP), renal function, electrolyte, blood gas and hemodynamic indicators were analyzed before, 12 h, 24 h, and 48 h after the initiation of CRRT and at the end of CRRT. Changes in neonatal renal function before, 24 h after the initiation of CRRT and at the end of CRRT were compared between the two groups. Efficacy of CRRT was evaluated, and clinical outcomes were analyzed. Kruskal-WallisH-test ort-test was applied for statistic analysis.Results(1) Among the 19 neonates with AKI, there were 12 in stage 1-2 and seven in stage 3. Seventeen cases were treated with CVVHDF, and the other two underwent plasma exchange. The duration of CRRT was 49-190 h with an average of (89.2±33.9) h. (2) After 12 h of CRRT, the blood pressure of all 19 AKI neonates returned to normal (40-60 mmHg, 1 mmHg=0.133 kPa) and was maintained at that level during the treatment. The blood pH value also increased to a normal range (7.35-7.45) at the same time. The oxygenation index reached 200 mmHg after 12 h of CRRT and rose to over 300 mmHg after 24 h. The levels of serum potassium, urea nitrogen, and creatinine decreased significantly after 12 h of CRRT and reached the normal range after 24 h of CRRT. After 24 h of CRRT, the urine volume significantly increased. (3) Serum levels of urea nitrogen and creatinine in neonates with AKI stage 1-2 decreased significantly after 24 h of CRRT. At any time points before and after CRRT (24 h before, 24 h after and at the end of CRRT), serum levels of urea nitrogen and creatinine in AKI stage 3 neonates were higher than those in AKI stage 1-2 neonates [urea nitrogen: (15.8± 4.1) mmol/L vs (10.2±5.1) mmol/L, (11.5±2.4) mmol/L vs (6.3±2.3) mmol/L, (9.8±2.1) mmol/L vs (5.1± 2.2) mmol/L,t=2.468, 2.226 and 2.171, respectively; creatinine: (184±32) μmol/L vs (152±26) μmol/L, (110±35) μmol/L vs (87±25) μmol/L, (63±12) μmol/L vs (44±9) μmol/L,t= 2.404, 2.423 and 3.972, respectively; allP<0.05]. (4) Venous catheterization was successful in the 19 AKI neonates. Three cases were complicated with thrombocytopenia, two with obstruction and two with hypotension during CRRT. Complications such as hypothermia, hemorrhage, thrombosis, and infection were not reported. (5) Among the 19 AKI neonates, 12 (including five of severe asphyxia, five of septic sepsis and two of inherited metabolic disorders and in metabolic crisis) were cured and discharged. The other seven cases (two in stage 1-2 and five in stage 3) lived through the oliguria stage but died after their family members gave up the treatment.ConclusionsCRRT is a safe and effective management for neonatal AKI. The optimal opportunity for CRRT treatment in AKI neonates should be at stage 1-2.