Parenteral Nutrition Components and Requirements
Posted by Surgery on Sep 9, 2008
Composition of Parenteral Nutrition
PN is a source of macronutrients (amino acids, dextrose, lipid emulsions), micronutrients (multivitamins, trace minerals), fluids, and electrolytes.
Pediatric parenteral crystalline amino acid formulas provide essential and nonessential amino acids specifically balanced to meet the needs of the developing child. 
Neonatal-specific amino acid formulas (Aminosyn PF, Trophamine) are formulated to closely reproduce the plasma amino acid profile of breastfed infants. These formulas have led to greater weight gain and improved nitrogen balance in infants compared with standard amino acid formulas. Some amino acids such as cysteine, tyrosine, glycine, and taurine are considered conditionally essential to the child (Table 7-2). Taurine supplementation to premature infants is essential to promote bile acid conjugation and improve bile flow. Premature infants are at risk for taurine deficiency as a result of relatively high renal excretion and low synthetic capacity related to diminished cystathionase enzyme activity and can leap to inadequate retinal development (17). Amino acids are a source of energy (4 kcal per g) and nitrogen for protein synthesis. Parenteral amino acids should approximately provide 10% to 15% of total calories. Amino acids are generally started at 1 g per kg per day and advanced to goal over 2 to 3 days. To simulate intrauterine protein accretion rate, low birth weight infants may need up to 3.85 g per kg per day of amino acids (6,18). Amino acid requirements are 2.5 to 3 g per kg per day in term infants, 1.5 to 2 g per kg per day in older children, and 1 to 1.5 g per kg per day in adolescents. Amino acid doses should be adjusted based on the patient’s clinical condition and nutritional status. For example, higher amino acid doses may be required to heal a complex wound. Patients with liver failure require lower amino doses to avoid hyperammonemia. Higher amino acid doses are required in patients on renal dialysis or continuous renal replacement therapies to compensate for losses via the dialysis membrane and filter (19,20).
Neonatal-specific amino acid formulas (Aminosyn PF, Trophamine) are formulated to closely reproduce the plasma amino acid profile of breastfed infants. These formulas have led to greater weight gain and improved nitrogen balance in infants compared with standard amino acid formulas. Some amino acids such as cysteine, tyrosine, glycine, and taurine are considered conditionally essential to the child (Table 7-2). Taurine supplementation to premature infants is essential to promote bile acid conjugation and improve bile flow. Premature infants are at risk for taurine deficiency as a result of relatively high renal excretion and low synthetic capacity related to diminished cystathionase enzyme activity and can leap to inadequate retinal development (17). Amino acids are a source of energy (4 kcal per g) and nitrogen for protein synthesis. Parenteral amino acids should approximately provide 10% to 15% of total calories. Amino acids are generally started at 1 g per kg per day and advanced to goal over 2 to 3 days. To simulate intrauterine protein accretion rate, low birth weight infants may need up to 3.85 g per kg per day of amino acids (6,18). Amino acid requirements are 2.5 to 3 g per kg per day in term infants, 1.5 to 2 g per kg per day in older children, and 1 to 1.5 g per kg per day in adolescents. Amino acid doses should be adjusted based on the patient’s clinical condition and nutritional status. For example, higher amino acid doses may be required to heal a complex wound. Patients with liver failure require lower amino doses to avoid hyperammonemia. Higher amino acid doses are required in patients on renal dialysis or continuous renal replacement therapies to compensate for losses via the dialysis membrane and filter (19,20).
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