Intravenous Amino Acid Therapy for Kidney Protection in Cardiac Surgery.

To date, no pharmacological agents are proven efficacious in treating perioperative AKI. There is a strong biological rationale for the administration of amino acid in the management of patients at risk of AKI with increases in renal blood flow and GFR of 25 to 60% for several hours after the administration of amino acids (Woods LL 1993) mediated by a afferent arteriolar dilation.(Meyer TW 1983) Moreover, animal models have demonstrated that an increase in renal blood flow in response to a short-term amino acid infusion can protect the kidney from acute ischemic insults. Finally, these nephro-protective effects are preserved in critical illness. Cardiac surgery appears to be the best setting to test the likely beneficial renal effects of amino acid because of pathophysiological principles and the ability to intervene before the injury has begun. Although the etiology of AKI in cardiac surgery is multifactorial, renal hypoperfusion is believed to play a major role in this development by decreasing renal perfusion through a reduction in renal blood flow and through the activation of the sympathetic nervous system and the renin-angiotensin system with afferent arteriolar vasoconstriction. In this setting, a global increase in renal blood flow by means of Amino Acid therapy appears a logical and promising intervention.

The primary aim of the study is to determine whether providing continuous infusion of a balanced mixture of amino acids, compared to placebo (balanced crystalloid solution), reduces the incidence of acute kidney injury (AKI) in patients scheduled for cardiac surgery defined as KDIGO stage 1 or greater during hospital stay.