Branched chain amino acid enriched parenteral nutrition in surgical intensive care patients

Prospective study on the efficacy of branched-chain amino acids in septic patients

The metabolic response to sepsis is characterized by increased proteolysis and gluconeogenesis, reduced protein synthesis, and negative nitrogen balance. The effects of a solution with a high proportion of branched-chain amino acids (BCAA) on the nutritional state of septic patients were evaluated. Eighty patients with peritonitis were divided into two groups of 40 patients; group 1 was administered a solution with 22.5% BCAA and group 2 with 45% BCAA. The following parameters were evaluated: anthropometrics, creatinine/height index, urinary 3-methylhistidine, nitrogen balance, stress index, albumin, prealbumin, transferrin, retinol binding protein, lymphocytes, delayed cutaneous sensitivity tests, studies of hepatic function, and plasma aminogram. In group 2 a more positive nitrogen balance, a greater drop in the stress index, a rise in plasma prealbumin and retinol binding protein levels, an increase in the creatinine/height index, and a more marked fall in the urinary excretion of 3-methylhistidine were found. When solutions with a high BCAA content were administered, there was an increase in the plasma concentrations of these amino acids in the BCAA/aromatic amino acid quotient and a decrease in the aromatic amino acids. Plasma concentrations of leucine and valine achieved very high, potentially toxic, levels at 15 days when solutions with high BCAA content were used. It is concluded that solutions with BCAA are advisable for use in the septic patient in the increased protein catabolic phase, where positive nitrogen balance, a reduction in muscle protein catabolism, and faster recovery of muscle and visceral protein were obtained.

Anticatabolic properties of branched chain amino-acids in post-operative patients. A prospective study

The effect of infusion of branched chain amino-acids (BCAA) on post-operative protein metabolism was analysed in 19 elective surgical patients treated for the first 5 post-operative days with a nutritional regimen of 30 kcal kg(-1) day(-1) and 2 g of amino-acids kg(-1) day(-1). The patients were divided into three groups whose only difference was the amount of BCAA delivered. Our results showed that an increased BCAA input improved nitrogen balance and reduced protein catabolism as estimated by the excretion of 3-methyl-histidine. Since nitrogen retention was maximal during the first 3 post-operative days and the reduction in 3-methylhistidine excretion was observed only on post-operative days 4 and 5, a dual action of BCAA on improving protein synthesis and reducing catabolism is postulated, even though the reduction in catabolism seems to be the main action. This dual action may reflect the unique role of BCAA, which is both 'nutritional' (as they constitute 40% of total amino-acid daily requirements of the healthy subject) and 'pharmacological (as they reduce protein catabolism and improve synthesis in muscle and liver with a dose-dependent effect). Of the three BCAA, isoleucine and leucine seemed to have an 'anticatabolic' effect, whereas an analysis of literature data showed that valine probably has none.

Impaired utilization of exogenous amino acids after surgery for subarachnoid haemorrhage

We studied the metabolic response to acute aneurysm surgery and its modification by parenteral nutrition. Forty-eight patients receiving perioperative corticosteroid treatment were randomly assigned to receive glucose alone (7.2 kcal/day, D5W + C), glucose and a conventional amino acid solution (7.2 kcal/day and 0.15 gN/day, CAA + C) or glucose and branched chain amino acid enriched solution (7.2 kcal/day and 0.14 gN/day, BCAA + C). Twenty patients without corticosteroid treatment received either glucose alone (7.2 kcal/day, D5W) or glucose and a conventional amino acid solution (7.2 kcal/day and 0.14 gN/day, CAA). Poor nitrogen utilization was indicated by strongly negative nitrogen balance in all groups and a failure of the infused amino acids to improve nitrogen balance. (Day 0; D5W + C: -9.3 +/- 3.6 g/day and CAA + C: -8.2 +/- 9.7 g/day vs CAA: -2.6 +/- 4.9 g/day, p less than 0.05, Day 1; D5W + C: -14.9 +/- 9 g/day vs CAA: -7.7 +/- 6.5 g/day, p less than 0.05, MANOVA). We conclude that subarachnoid haemorrhage and its surgical treatment induce a catabolic response and impaired utilization of exogenous nitrogen, further amplified by perioperative corticosteroids, which is in sharp contrast to the response to surgery not involving the central nervous system.