MEDizzy - A 66-year-old, 70-kg man undergoes extensive small bowel

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Surgical Nutrition

A 66-year-old, 70-kg man undergoes extensive small bowel resection for mesenteric ischemia and receives parenteral nutritional support. He is receiving 5 g/kg/day of carbohydrates, 0.2 g/kg/day of nitrogen, and 0.6 g/kg/day of lipids. Which of the following most closely approximates the number of calories this patient is receiving each day?

ExplanationD. Carbohydrates produce ~ 4 kcal/g of substrate while lipids produce ~ 9 kcal/g substrate. Proteins produce ~ 4 kcal/g of substrate as well. Protein content may be frequently expressed as grams of nitrogen: 6.25 g of protein = 1 g of nitrogen. Therefore 0.2 g/kg/day of nitrogen = 1.25 g/kg/day of protein. Using these values, this patient is receiving approximately [(4 kcal/g × 5 g carbohydrates) + (9 kcal/g × 0.6 g lipids) + (4 kcal/g × 1.25 g protein)] × 70 kg = 2128 kcal/day.