To compare the effects of fluid bolus therapy (FBT) with 20% albumin to crystalloid FBT on the incidence of cardiac surgery–associated acute kidney injury (CSA-AKI) and its severity and duration.

Secondary analysis of the multicenter, parallel-group, open-label, randomized HAS FLAIR-II trial.

Six intensive care units.

Patients who required clinician-determined FBT after cardiac surgery requiring cardiopulmonary bypass.

Patients were randomized to receive FBT with 20% albumin (up to 400 mL/day) or crystalloid fluid for all FBTs in the intensive care unit.

A total of 452 patients were included in the modified intention-to-treat population (224 in the 20% albumin group and 228 in the crystalloid group). AKI occurred in 54 (24%) patients in the 20% albumin group and 50 (22%) in the crystalloid group (odds ratio: 1.13, 95% confidence interval [CI]: 0.73 to 1.76). However, in patients who developed stages 2 and 3 AKI, those allocated to 20% albumin had a significantly lower median time-weighted average (TWA) creatinine: 144 µmol/L (interquartile range [IQR]: 109 to 162) versus 254 µmol/L (IQR: 182 to 294) than the crystalloid group (difference –105 µmol/L, [95% CI –170 to –41], p = 0.003) and a lower peak serum creatinine (–110 µmol/L [–189 to –32], p = 0.01). The reduced TWA creatinine in the 20% albumin group was seen in patients with both a low (p = 0.04) and normal preoperative serum albumin concentration (p < 0.001).

FBT with 20% albumin compared with crystalloid-based regimen did not reduce the occurrence of AKI in patients after cardiac surgery. However, it reduced the severity and duration of stages 2 and 3 AKI.