Fluid infusion is restricted at 2 ml·kg- 1·h- 1 from the moment the patient arrive in the operating room to immediately after the liver lesions are removed

Postoperative acute kidney injury (AKI) was diagnosed and staged according to the Kidney Disease: Improving Global Outcomes (KDIGO) Clinical Practice Guideline for Acute Kidney Injury (2012). AKI was defined as the presence of any of the following criteria within 7 days after surgery: an increase in serum creatinine by ≥ 0.3 mg/dL (≥ 26.5 μmol/L) within 48 hours; an increase in serum creatinine to ≥ 1.5 times baseline, which is known or presumed to have occurred within the prior 7 days; or urine volume < 0.5 mL/kg/h for 6 consecutive hours. Baseline serum creatinine was defined as the most recent preoperative value available within 3 months prior to surgery.

AKI severity was further classified into three stages: stage 1 was defined as serum creatinine 1.5-1.9 times baseline or an increase of ≥ 0.3 mg/dL (≥ 26.5 μmol/L), or urine output < 0.5 mL/kg/h for 6-12 hours; stage 2 as serum creatinine 2.0-2.9 times baseline, or urine output < 0.5 mL/kg/h for ≥ 12 hours; and stage 3 as serum creatinine 3.0 times baseline, or an increase in serum creatinine to ≥ 4.0 mg/dL (≥ 353.6 μmol/L), or initiation of renal replacement therapy, or urine output < 0.3 mL/kg/h for ≥ 24 hours, or anuria for ≥ 12 hours