Douglas Bag Method

**Semantic type:** Diagnostic Procedure

**Definition:** An indirect calorimetry system that is used to estimate respiratory gas exchange as a surrogate for energy expenditure during metabolism. All of a subject's undiluted expired air is collected in a large, impermeable canvas bag over a timed period, and chemical gas analysis is used to determine the rate of oxygen uptake (VO2) and carbon dioxide production (VCO2).

**Synonyms:** - Douglas Bag - Douglas Bag Indirect Calorimetry - Douglas Bag Technique