1. Oxidative metabolism has been studied by indirect calorimetry in 42 patients within the first 6 h after accidental injury.
2. the level of energy expenditure bore no relationship to the severity of the injury and varied more widely from patient to patient than in normal subjects.
3. After minor and moderate injuries the respiratory exchange ratio (mean 0.86) was not different from that in normal subjects on a mixed diet. After severe injuries the ratio (mean 0.78) was significantly lower (P < 0.005), indicating that the main substrate for oxidation in these patients was fat, despite their hyperglycaemia.