Prediction equations to determine caloric requirements in critically ill patients.

The ability to predict resting energy expenditure in a given individual during critical illness is very difficult. The unreliability of prediction equations to determine caloric requirements in critically ill patients is well established.1-17 The stress response to a specific insult is not identical across individuals, which further impairs the accuracy of prediction equations. Even the variables used in the prediction equations may be difficult to determine. Obesity, excess body water, and critical illness cloud the ability to choose a body weight variable. Population differences of ethnicity, age, and height limit the suitability of prediction equations to accurately determine resting energy expenditure in certain individuals.