Nitrogen retention in critically ill patients is proportional to the branched chain amino acid load.

The nitrogen retention effect of branched chain enriched parenteral nutrition (BcAA) during surgical stress and polytrauma was evaluated in a prospective, randomized, double blind study in 32 patients. The doses of BcAA were 0.16, 0.3, 0.5, and 0.7 g/kg . day with a total amino acid load of 1 or 1.5 g/kg . day. It was provided in a setting of 30 glucose cal/kg . day with 7 cal/kg . day of iv fat also given to 16 patients. After the 7-day study was completed, analysis of the 4 treatment groups of 8 patients each demonstrated that there was an increased nitrogen retention effect of BcAA, that the effect was proportionate to BcAA load, that the effect started at 0.5 g of BcAA/kg . day in a setting of balanced nutritional support, and that the effect was consistent with a BcAA influence on protein synthesis. There were no complications or side-effects from high dose BcAA. Metabolic support of the stress response in ICU patients has become a clinical reality.