Amino Acid Concentrations in Critically Ill Children Following Cardiac Surgery*

Abstract

Circulating amino acid concentrations in critically ill children after cardiac surgery differ according to survival status, blood glucose control with intensive insulin therapy, and age.

Proteins and amino acids are fundamental to optimal nutrition support in critically ill patients

“…As long as these processes remain adaptive, plasma AA levels remain stable and in balance. However, when the stress response becomes too intense and persists for too long, the balanced AA profile in plasma is disrupted, resulting in abnormal AA concentrations (both higher and lower levels than normal) [ 25 - 27 ]. In particular, plasma glutamine concentrations have been associated with unfavorable outcomes in critically ill patients [ 28 , 29 ].…”

How to Monitor and How to Decrease Protein Hypercatabolism in Critically Ill Children?

“…They evidenced a lesser negative nitrogen balance and similar benefits, mainly in the first 72 hours of critical illness, in a group with moderate insulin therapy with a lower prevalence of hypoglycemia comparing to Gielen et al (4).…”

“…Despite certain reservations regarding the accuracy of nitrogen balance, it may provide a better estimation of protein loss (2,4). The measurement of amino acids profile without other nutritional variables might not be the best way to predict and calculate protein catabolism; furthermore, it behaves differently in postsurgical cardiac patients (1).…”

“…Gielen et al (4) hypothesized that higher amino acid concentration profiles could be a sign of hypercatabolism, but no other measurements of protein balance or other nutritional comparison were considered, bar the assessment of body mass index. Despite certain reservations regarding the accuracy of nitrogen balance, it may provide a better estimation of protein loss (2,4).…”

The author replies

“…Remarkable differences in total plasma amino acid concentrations and the concentrations of individual amino acids at admission and during ICU stay according to survival status (higher in nonsurvivors) and age (higher in neonates when compared with older infants and children) were reported in children following cardiac surgery (12). In another study aimed at investigating arterial plasma concentrations of amino acids during systemic inflammation in children, arginine and citrulline (a functional biomarker of enterocyte mass and precursor of arginine) were shown to be low during the acute phase of critical illness and normalized during recovery.…”