Renal effects of amino acid infusion in cardiac surgery

Objective: To evaluate effects of amino acids on renal function and oxygen consumption and the role of individual amino acids on renal blood flow (RBF ) changes. Design: Prospective, randomized, controlled study. Setting: Operating room in cardiothoracic surgery department, university ho spital. Participants: Twenty-two male patients submitted to elective first-time cor onary artery bypass surgery. Interventions: A catheter was placed in the left renal vein for thermodilut ion RBF measurements and blood sampling. In 11 patients, a balanced mixed a mino acid infusion was infused (200 mL/hr) for 30 minutes immediately after the operation. Measurements and Main Results: RBF and glomerular filtration rate increased during amino acid infusion compared with the control group. Renal oxygen c onsumption increased in the amino acid group and correlated with the increa se in RBF (r = 0.70, p < 0.001). Amino acid infusion induced two- to fourfo ld increases in plasma concentrations of individual amino acid concentratio ns and promoted renal extraction of aspartate, glutamate, glycine, and hist idine. No correlation was observed between arterial concentration or uptake of individual amino acids and RBF. Conclusions: The increase in RBF from a mixed amino acid infusion was assoc iated with increased glomerular filtration rate and renal consumption of ox ygen. Changes in RBF of a mixed amino acid infusion could not be linked to plasma level or renal uptake of any individual amino acids. Copyright (C) 2 000 by W.B. Saunders Company.