Indirect calorimetry is the standard for determination of RMR in critically ill patients. When indirect calorimetry cannot be performed, predictive formulas may be necessary.

 

 

 

 

 

 

 

 

 

 

Six studies including individuals with obesity, studied the application of several predictive equations and the use of actual or adjusted body weight.  One study, based on hospitalized patients, reported that the Harris-Benedict equation using actual weight multiplied by a factor of 1.2 (60% of subjects predicted within 10% of RMR) or an adjusted weight multiplied by a factor of 1.3 (67% of subjects predicted within 10% of RMR) resulted in the most accurate predictions.  A second study, based on critically ill, mechanically ventilated patients, reports that the Penn State 2003a equation predicts within 10% of RMR in 61% of subjects, the Penn State 1998 equation predicts within 10% of RMR in 67% of subjects, and the Ireton-Jones, 1992 equations predict within 10% of RMR in 72% of subjects.  Further research is needed in critically ill patients with obesity.