Evolution of energy expenditure and nitrogen excretion in severe head-injured patients.
 OBJECTIVE: The aim of the study was to estimate the influence of therapeutic changes on the level of energy expenditure (EE) and N excretion in a homogeneous group of patients usually considered hypermetabolic.
 DESIGN: EE and N excretion of head-injured patients were measured simultaneously at phases 1 and 2 (patients treated 4 +/- 3 and 18 +/- 8 days after injury, respectively).
 SETTING: Acute care hospital.
 PATIENTS: Eight severe head-injured patients, mean weight 63.1 +/- 6.1 (SD) kg, mean age 21 +/- 3.8 (SD) yr.
 INTERVENTIONS: At phase 1, all patients were sedated with fentanyl (6.7 +/- 1.9 micrograms/kg.hr) plus flunitrazepam (9.1 +/- 4.8 micrograms/kg.hr) and were mechanically ventilated.
 All patients received continuous total parenteral nutrition.
 The nonprotein caloric intake averaged 1092 +/- 200 kcal/day, including 77% glucose and 23% fat (Intralipid 20%).
 The total N intake averaged 7 +/- 5 g/day, consisting of crystalline amino acids.
 At phase 2, no patient received any sedative and all were breathing spontaneously via tracheostomy.
 All patients received parenteral and/or enteral nutrition.
 The nonprotein caloric intake averaged 1929 +/- 200 kcal/day consisting of 65% carbohydrates and 35% fat.
 The total N intake averaged 13 +/- 2 g/day.
 MEASUREMENTS AND MAIN RESULTS: The EE was significantly higher at phase 2 than at phase 1 (2121 vs.
 1737 kcal), but the interindividual variability was low at both phases.
 N excretion was high at the two periods of the study and not correlated to the level of EE.
 The RQ was 0.75 at both periods, indicating predominant fat oxidation.
 CONCLUSIONS: We could not demonstrate any parallelism in the evolution of EE and protein catabolism in head-injured patients.
 The therapeutics (mechanical ventilation, sedation, and nutrition) have a major effect on EE but little on N excretion.
