Postoperative parenteral nutrition with high supply of branched-chain amino acids: effects on nitrogen balance and liver protein synthesis

Hepatobiliary complications of total parenteral nutrition

The relationships between various hepatobiliary disorders and the administration of total parenteral nutrition (TPN) were reviewed and, in particular, the role of TPN in their pathogenesis was critically evaluated. Several clinical and pathological entities including steatosis, steatohepatitis, cholestasis, and cholelithiasis have been commonly linked to TPN, and instances of chronic decompensated liver disease have been reported. However, it is concluded that it is often difficult to extricate the effects of TPN on hepatobiliary function from many other hepatotoxic factors that may be operative in these patients. Thus, whereas considerable evidence exists to support a role fro carbohydrate or calorie excess in TPN solutions in the pathogenesis of steatosis, a loss of enteric stimulation and not TPN per se may be the primary factor in the development of cholestasis, biliary sludge, and gallstones. The apparent predilection of infants to TPN-related cholestasis may be based on the relative immaturity of the neonatal biliary excretory system.

The impact of leucine infusion on skeletal muscle amino acid and energy metabolism in severely traumatized patients

The response to trauma is associated with increased energy requirements and net protein breakdown. The branched chain aminoacids, especially leucine, are considered to act by serving as a fuel for muscle tissue and by stimulating synthesis of proteins and controlling protein breakdown. Such results have been obtained mainly from in vitro studies. The present study was designed to evaluate the pharmacological effect of leucine infusion on muscle energy/amino acid metabolism in man after severe multiple trauma. 16 patients were studied and randomly allocated into 2 groups. Group 1 was given fat and 20% glucose while group 2 received 6 g N in form of leucine dissolved in 10% glucose solution and fat. The patients received 40 kcal/kg/24 h over an 8 day period after trauma. Biochemical analyses, muscle biopsies (energy substrates, electrolytes, amino acids), nitrogen balance and 3-methyl histidine excretion in urine were evaluated. Biochemical data revealed a significant increase (p < 0.05) of serum urea in group 2 day 4 and 8 after trauma. Muscle intracellular electrolytes (K(+), Mg(2+)) and energy substrates (ATP, phosphocreatine) showed a similar decrease in both groups. The intracellular muscle amino acids displayed a pattern known to be related to trauma without differences between the groups. The cumulative nitrogen balance 8 days after the injury was -93.5 g N +/- 10.1 (SEM) in group 1 and -73 g N +/- 7.5 in group 2. The 3-methylhistidine excretion was markedly increased similar in both groups. The present study demonstrated no significant pharmacological effect of leucine administration on muscle metabolism, nitrogen balance or 3-methylhistidine excretion in severely traumatized patients. Conventional balanced amino acid solutions are probably optimal to meet the patients actual requirements.

Metabolic effect of short-term total parenteral nutrition highly enriched with leucine or valine in rats recovering from severe trauma

The metabolic impact of infusing a large amount of leucine (Leu) or valine (Val) was examined with regard to the corrective effect of total parenteral nutrition (TPN). Rats recovering from severe sepsis received either Leu- or Val-enriched TPN solution for 30 hours. The in vivo behavior of the amino acids administered was explored by a pulse injection of 14C-labeled Leu or Val. The recovery of 14CO2 from Leu increased by 64% in the septic rats of Leu-TPN group (41% of dose; p less than .01), as compared with control rats receiving the same TPN solution, whereas no significant rise in the 14CO2 recovery from Val occurred in the septic rats given Val-TPN (45% of dose) in comparison with the corresponding controls. The enhancement of Leu catabolism to CO2 in the Leu-TPN group was compatible with the alterations of urinary nitrogen excretion, plasma Leu level, and metabolite contents of liver and muscle. The only difference in metabolite levels observed between the two TPN groups was in hepatic total adenine nucleotides. Plasma amino acid levels were largely unaffected by infusion of these TPN solutions highly enriched with branched-chain amino acids (45%), except for an approximately threefold elevation of the Val level in Val-TPN rats. Thus, when administered in a large quantity during such short-term TPN, Leu can exert its metabolic effect without causing an imbalance in plasma amino acids under severe catabolic conditions.

Long-term oral branched-chain amino acid treatment in chronic hepatic encephalopathy. A randomized double-blind casein-controlled trial. The Italian Multicenter Study Group

In a double blind randomized study, branched-chain amino acids and placebo (casein) were compared as a treatment for chronic hepatic encephalopathy in cirrhosis. After a 15-day run-in period with controlled diet (45-65 g protein), the patients were administered, in addition to their diet, branched-chain amino acids (0.24 g/kg, 30 patients) or an equinitrogenous amount of casein (34 patients). One patient on branched-chain amino acids and two on casein were lost to the study. After 3 months, the index of portal-systemic encephalopathy significantly improved in patients on active treatment (from 40 [S.D. 14]% to 21 [17]), but was not in subjects receiving casein (from 37 [13]% to 36 [12]). Two or more parameters of the index improved in 24 patients treated with amino acids (80%; confidence limits, 61-92%), and only in 12 receiving casein (35%; confidence limits, 20-54%; p less than 0.001). Patients who did not improve were given an alternative treatment for 3 more months. Casein-treated patients given branched-chain amino acids rapidly improved. The changes in neuropsychologic function were associated with an improvement in semiquantitative nitrogen balance, which became consistently positive in amino acid-treated subjects; there was also a mild improvement in nutritional parameters and in liver function tests. The supplementation of oral branched-chain amino acids to the diet is superior to casein as a treatment for providing adequate nitrogen supply and improving the mental state of cirrhotic patients with chronic encephalopathy.

Immediate stimulation of protein metabolism in burned rats by total parenteral nutrition enriched in branched-chain amino acids

The effects of two kinds of total parenteral nutrition (TPN) on energy and protein metabolism were examined in rats subjected to 15% full-thickness scald burns in the absence of septic complications. One type of TPN was enriched in branched-chain amino acids (BCAAs), especially leucine (45% BCAA content), and the other was conventional TPN (21% BCAA content). Burned rats received isocaloric and isonitrogeneous TPN solutions for 48 hr after resuscitation by saline infusion for 24 hr. Liver and rectus abdominis muscle were removed from the rats at 7, 24, 48, and 72 hr. The concentrations of adenine nucleotides, RNA, protein, glucose-6-phosphate, hepatic glycogen, muscle phosphocreatine, and 3-methylhistidine were determined. Metabolic alterations occurred during the period of saline resuscitation (0-24 hr). At 48 hr the RNA and protein levels were significantly more improved in the BCAA-TPN group than in the conventional TPN group. At 72 hr, however, the results for the two groups were similar in most metabolite levels. Thus, BCAA-TPN enriched in leucine rapidly stimulated protein synthesis in the liver and muscle. This rapid effect may make it useful during the initial nutritional management of severe trauma patients.

A key to the literature of total parenteral nutrition: update 1987

This comprehensive bibliography is intended to enhance the education of the practitioner, student, and academician in the area of parenteral nutrition. This bibliography is not all-inclusive but serves as an update from the original published in 1983. Of particular note in this work is the addition of topics that reflect a growing interest in medical specialties with regard to patient nutritional status and support.