Table 3.
Suggested Parenteral-Nutrition Requirements for Critically Ill Adult Patients.*
| Variable | Dose† |
|---|---|
| Energy | Resting energy expenditure in kcal/day × 1.0 to 1.2, or 20 to 25 kcal/kg/day‡ |
| Dextrose | Initial parenteral nutrition order with 60 to 70% of non–amino acid calories as dextrose§ |
| Lipid emulsion | Initial parenteral nutrition order with 30 to 40% of non–amino acid calories as lipid§ |
| Essential and nonessential amino acids (g/kg/day) | |
| Normal renal and hepatic function | 1.2–1.5¶ |
| Hepatic failure (cholestasis) | 0.6–1.2 (based on estimated function) |
| Encephalopathy | 0.6 (may be temporarily discontinued) |
| Acute renal failure in patients not on renal-replacement therapy | 0.6–1.0 (based on renal function) |
| Renal failure in patients on renal-replacement therapy | 1.2–1.5∥ |
Caloric needs can be estimated by indirect calorimetry; they can be inaccurate in mechanically ventilated patients receiving high levels of inspired oxygen or because of air leaks or other technical issues. In obese subjects, an adjusted body weight should be used in the calculation of energy and protein needs according to the following equation: Adjusted body weight = ideal body weight (from standard tables or equations) + (current weight − ideal body weight) × 0.25.
The energy density is 3.4 kcal per gram for dextrose, 10 kcal per gram for lipid emulsion, and 4 kcal per gram for amino acids.
The Harris–Benedict equation can be used to estimate resting energy expenditure in kcal per 24 hours and for men is as follows: 66.5 + (13.8 × body weight in kg) + (5.0 × height in cm) − (6.8 × age in yr). The equation for women is: 655 + (9.6 × body weight in kg) + (1.8 × height in cm) − (4.7 × age in yr). The equation may over- or underestimate resting energy expenditure in certain critically ill patients, particularly when clinical conditions are changing and when body weight fluctuates because of changes in fluid status.
Caloric needs can also be estimated as 20 to 25 kcal per kilogram per day (using dry weight or ideal body weight). Some studies suggest that 15 to 20 kcal per kilogram per day or lower may be appropriate.
The clinical practice guidelines of some professional societies recommend protein or amino acid doses up to 2.0 g per kilogram per day in certain subgroups.
The clinical practice guidelines of some professional societies recommend protein or amino acid doses up to 2.0 or 2.5 g per kilogram day in patients receiving renal-replacement therapy.