Measured versus Predicted Energy Expenditure in Mechanically Ventilated Patients with Chronic Obstructive Pulmonary Disease

Abstract

Adequate provision of nutritional support to hospitalized patients is an important goal, and effectively determining nutritional needs is the first step toward this goal. Such determination calls for either predicting or measuring energy expenditure. We studied the relationship between predicted resting energy expenditure (PREE) and measured resting energy expenditure (MREE) in patients with chronic obstructive pulmonary disease (COPD) who required mechanical ventilation. Method: We studied 19 mechanically ventilated adult patients with COPD. In each patient, PREE was determined by the Harris-Benedict equation and MREE by indirect calorimetry, utilizing the Weir method. Results: We found a poor correlation between PREE and MREE (r = 0.174). Further analysis revealed a MREE-PREE variation of 88-146%, with mean MREE being 121% of mean PREE. The relationship between MREE and PREE was not affected by the mode of ventilation or type of nutritional support. Conclusion: Because the caloric requirements of these mechanically ventilated patients with COPD were greater than predicted by the Harris-Benedict equation, we suggest that measurement of resting energy expenditure is superior to the use of standard prediction equations in prescribing nutritional support.