nutritional disorders
Total Parenteral Nutrition (TPN)
Nutritional content
TPN requires water (30 to 40 mL/kg/day), energy (30 to 35 kcal/kg/day, depending on energy expenditure; up to 45 kcal/kg/day for critically ill patients), amino acids (1.0 to 2.0 g/kg/day, depending on the degree of catabolism), essential fatty acids, vitamins, and minerals (see table Basic Adult Daily Requirements for Total Parenteral Nutrition ). Children who need TPN may have different fluid requirements and need more energy (up to 120 kcal/kg/day) and amino acids (up to 2.5 or 3.5 g/kg/day). Basic TPN solutions are prepared using sterile techniques, usually in liter batches according to standard formulas. Normally, 2 L/day of the standard solution is needed. Solutions may be modified based on laboratory results, underlying disorders, hypermetabolism, or other factors. Most calories are supplied as carbohydrate. Typically, about 4 to 5 mg/kg/minute ofdextroseis given. Standard solutions contain up to about 25%dextrose, but the amount and concentration depend on other factors, such as metabolic needs and the proportion of caloric needs that are supplied by lipids. Commercially available lipid emulsions are often added to supply essential fatty acids and triglycerides; 20 to 30% of total calories are usually supplied as lipids. However, withholding lipids and their calories may help obese patients mobilize endogenous fat stores, increasinginsulinsensitivity. 