Chapter 073. Enteral and Parenteral Nutrition (Part 7)

Protein or Amino Acid RequirementsAlthough the recommended dietary allowance for protein is 0.8 g/kg per d, maximal rates of repletion occur with 1.5 g/kg in the malnourished. In the severely catabolic patient, this higher level minimizes protein loss. In patients requiring SNS in the acute care setting, at least 1 g/kg is recommended, with greater amounts up to 1.5 g/kg as volume, renal, and hepatic tolerances allow. The standard parenteral and enteral formulas contain protein of high biologic value and meet the requirements for the eight essential amino acids. In protein-intolerant conditions such as renal and hepatic failure, modified...
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Chapter 073. Enteral and Parenteral Nutrition (Part 7) Chapter 073. Enteral and Parenteral Nutrition (Part 7) Protein or Amino Acid Requirements Although the recommended dietary allowance for protein is 0.8 g/kg per d,maximal rates of repletion occur with 1.5 g/kg in the malnourished. In the severelycatabolic patient, this higher level minimizes protein loss. In patients requiringSNS in the acute care setting, at least 1 g/kg is recommended, with greateramounts up to 1.5 g/kg as volume, renal, and hepatic tolerances allow. Thestandard parenteral and enteral formulas contain protein of high biologic value andmeet the requirements for the eight essential amino acids. In protein-intolerantconditions such as renal and hepatic failure, modified amino acid formulas shouldbe considered. In hepatic failure, higher branched-chain amino acid–enrichedformulas appear to improve outcomes. Conditionally essential amino acids likearginine and glutamine may also have some benefit in supplemental amounts. Protein (nitrogen) balance provides a measure of feeding efficacy of PN orEN. It is calculated as protein intake/6.25 because proteins are on average 16%nitrogen (N), minus the 24-h urine urea N (UUN) plus 4 g N, which reflects otherN losses. In the critically ill, a mild negative balance of 2–4 g N/d is usuallyachievable with a similarly mild positive balance in the recuperating patient. Eachg N represents approximately 30 g lean tissue. Mineral and Vitamin Requirements Parenteral electrolyte, vitamin, and trace mineral requirements aresummarized in Tables 73-4, 73-5, and 73-6. Electrolyte modifications arenecessary with substantial gastrointestinal losses from nasogastric drainage orintestinal losses from fistulas, diarrhea or ostomy outputs. Such losses also implyextra calcium, magnesium, and zinc losses. Excessive urine or potassium losseswith amphotericin, or magnesium losses with cisplatin or in renal failure,necessitate adjustments in sodium, potassium, magnesium, phosphorus, and acid-base balance. Vitamin and trace element requirements are met by the dailyprovision of a complete parenteral vitamin supplement and trace elements for PN,and with the provision of adequate amounts of enteral feeding formulas thatcontain these micronutrients.Table 73-4 Usual Daily Electrolyte Additions to Parenteral NutritionElectrolyte Parenteral Usual Intake Equivalent of RDASodium 1–2 meq/kg + replacement, but can be as low as 5–40 meq/dPotassium 40–100 meq/d + replacement of unusual lossesChloride As needed for acid-base balance, but usually 2:1 to 1:1 with acetateAcetate As needed for acid-base balanceCalcium 10 meq 10–20 meq/dMagnesium 10 meq 8–16 meq/dPhosphorus 30 mmol 20–40 mmolTable 73-5 Parenteral Multivitamin Requirements for AdultsVitamin Recently Revised ValueVitamin A 3300 IUThiamin (B1) 6 mgRiboflavin (B2) 3.6 mgNiacin (B3) 40 mgFolic acid 600 µg Pantothenic acid 15 mg Pyridoxine (B6) 6 mg Cyanocobalamin 5 µg(B12) Biotin 60 µg Ascorbic acid (C) 200 mg Vitamin D 200 IU Vitamin E 10 IU Vitamin Ka 150 µg a A product is available that does not containvitamin K. Vitamin K supplementation is recommendedat 2–4 mg/week in patients not receiving oralanticoagulation therapy if using this product.