Improvement in amino acid use in the critically ill patient with parenteral formulas enriched with branched chain amino acids

Document Type

Journal Article

Publication Date



Surgery Gynecology and Obstetrics






To assess the value of BCAA enriched solutions in patients under stress, we studied five critically ill, intensive care unit patients requiring total parenteral nutrition. Two complete feeding solutions were compared: one containing 15.6 per cent of the amino acids as BCAA and the other enriched to contain 50 per cent as BCAA. These solutions were prepared to be isocaloric and isonitrogenous and were administered in consecutive 24 hour periods. The order of administration was determined randomly. In the last ten hours of each infusion day, 50 microcuries of L-[1-14C]leucine were added to the solution to estimate leucine kinetics. Increased plasma leucine appearance (from 3.92 ± 0.48 to 6.26 ± 0.51 millimoles per hour, p < 0.05), oxidation (from 0.83 ± 0.23 to 1.41 ± 0.33 millimoles per hour, p < 0.05) and net leucine balance (from +0.48 ± 0.23 to +1.41 ± 0.33 millimoles per hour, p < 0.05) were found in patients while receiving the solution enriched to contain 50 per cent of the amino acids as BCAA. Plasma leucine, isoleucine and valine concentrations were also significantly increased when administration of the BCAA enriched solution, whereas plasma levels of glycine, tyrosine and phyenylalanine were significantly reduced. These changes represent a normalization of plasma amino acid levels with administration of BCAA enriched solution. In addition, the improved net leucine balance observed during administration of BCAA suggests patients have an improved protein balance while receiving BCAA enriched solutions.

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