Fig. 2
From: Strategies for optimal calorie administration in critically ill patients
Methods of calculating or estimating energy expenditures. Indirect calorimetry measures VO2 and VCO2 from respiratory gases via masks or tracheal tubes. Then, energy expenditure (EE) is calculated using the Weir equation. In addition, the respiratory quotient (RQ) is calculated by dividing VCO2 by VO2. EE and RQ values are shown in Fig. 1. VO2 oxygen consumption, VCO2 carbon dioxide production, W weight, H height