Intravenous amino acid therapy for kidney protection in cardiac surgery patients: A pilot randomized controlled trial.

OBJECTIVE: To determine whether a continuous intravenous infusion of standard amino acids could preserve kidney function after on-pump cardiac surgery.

METHODS: Adult patients scheduled to receive cardiac surgery lasting longer than 1 hour on-pump were randomized to standard care (n = 36) or an infusion of amino acids initiated immediately after induction of anesthesia (n = 33). The study's primary outcome measurements assessed renal function. These assessments included duration of renal dysfunction, duration and severity of acute kidney injury (AKI), estimated glomerular filtration rate (eGFR) over time, urine output, and use of renal-replacement therapy. Complications and other measures of morbidity were also assessed.

RESULTS: Sixty-nine patients (mean age 71.5 [standard deviation 9.2] years; 19 of 69 women) were enrolled and randomized. Patients received coronary artery bypass graft surgery (37/69), valve surgery (24/69), coronary artery bypass graft and valve surgery (6/69), or other procedures (2/69). Mean on-pump time was 268 [standard deviation 136] minutes. Duration of renal dysfunction did not differ between the groups (relative risk, 0.86; 95% confidence interval [CI], 0.19-3.79, P = .84). However, patients who received the amino acid infusion had a reduced duration of AKI (relative risk, 0.02; 95% CI, 0.005-0.11, P < .0001) and greater eGFR (+10.8%; 95% CI, 1.0%-20.8%, P = .033). Daily mean urine output was also significantly greater in patients who received the amino acid infusion (1.4 ± 0.5 vs 1.7 ± 0.9 L/d; P = .046).

CONCLUSIONS: Commencing an infusion of standard amino acids immediately after the induction of anesthesia did not alter duration of renal dysfunction; however, other key measures of renal function (duration of AKI, eGFR and urine output) were significantly improved. These results warrant replication in multicenter clinical trials.