Amino acid kinetics in patients with sepsis

Background: In patients with sepsis and systemic inflammatory response synd rome, amino acid extraction by the liver is enhanced, resulting in decrease d plasma amino acid concentrations. Systematic investigations of the elimin ation of intravenously infused amino acids have not been performed. Objective: The objective of this study was to compare the elimination of 17 amino acids in patients with sepsis and in healthy control subjects. Design: Elimination of amino acids was evaluated in 9 patients with sepsis and in 8 healthy control subjects by using a combined loading and maintenan ce infusion of 375 mg amino acids/kg body wt for 60 min. Pharmacokinetic va riables were analyzed from plasma curves. Results: With the exception of lysine, methionine, glutamate, ornithine, ph enylalanine, and tyrosine, plasma concentrations of amino acids were lower in the patients with sepsis than in the control subjects; phenylalanine was the only amino acid whose plasma concentration increased (P < 0.001). In p atients with sepsis, whole-body clearance (Cl-tot) of total amino acids was 74% higher than in control subjects (x) over bar +/- SEM: 13161 +/- 1659 a nd 7566 +/- 91 mL/min, respectively; (P < 0.01), the Cl-tot of essential am ino acids was 64% higher (P < 0.02), that of nonessential amino acids was 8 2% higher (P < 0.01), and that of both branched-chain amino acids and gluco genic amino acids was 97% higher (P < 0.001). With the exception of phenyla lanine, ornithine, proline, and glutamate, the Cl-tot of all amino acids wa s elevated. The Cl-tot of phenylalanine and ornithine decreased slightly (N S). Conclusions: In patients with sepsis, plasma concentrations of most amino a cids are greatly decreased and the elimination of amino acids from the intr avascular space during intravenous infusion is greatly enhanced.