Comparison of predicted and measured energy expenditure in mechanically ventilated obese patients

Objective: To test the appropriateness of using actual body weight (ABW), ideal body weight (IBW), or an adjusted weight for predicting caloric requirements in moderately obese, mechanically ventilated patients receiving parenteral or enteral nutrition. Design: Prospective, nonrandomized pilot study involving seven patients. Setting: University medical center. Main Outcome Measures: Predicted caloric requirements based on ABW, IBW, or an adjusted weight were compared with measured requirements by indirect calorimetry after parenteral nutrition or tube feedings were at goal rate for 24-72 hours. Results: Mean differences between predicted and measured energy requirements for ABW, IBW, and adjusted weight were 821 ± 556 (p < 0.05), - 256 ± 493, and 182 ± 501 kcal/d, respectively. Conclusions: Until additional studies are available, IBW or adjusted weight should be used for calculating caloric requirements in the moderately obese patient being mechanically ventilated when actual measurements are not available.