Influence of fever on the hypermetabolic response in burn-injured children

Background: Burn injury typically elicits a hypermetabolic response characterized by increased energy expenditure and muscle protein catabolism. Hypothesis: Fever further increases energy expenditure and muscle loss in otherwise highly hypermetabolic burn patients. Design: Retrospective analysis of experimental study. Setting: University hospital. Patients: Eighty-four children (aged 2-18 years) with burns covering 40% or more of total body surface area. Interventions: None. Main Outcome Measures: Simultaneous measurements of indirect calorimetry and leg net balance of phenylalanine (as an index of muscle protein catabolism) were obtained. Patients were stratified by their rectal temperature taken at the time of these metabolic measurements: afebrile (n=28; temperature, <39.0°C); mild fever (n=26; temperature, 39.0°C-39.4°C); moderate fever (n=18; temperature, 39.5°C-39.9°C); or severe fever (n=12; temperature, ≥40.0°C). Results: Febrile and afebrile patients were similar in age, body weight, and extent of burn area. Severe fever was associated with significantly increased resting energy expenditure (mean±SD resting energy expenditure-predicted basal, 1.38±0.39 for afebrile patients vs 1.68±0.30 for patients with severe fever; P<.05) and a greater net loss of phenylalanine from the leg (net balance of phenylalanine, -6.0±6.2 mg/min per 100 mL of leg volume for afebrile patients vs - 10.8±7.2 mg/min per 100 mL for patients with severe fever; P<.05). Patient groups were similar in plasma glucose concentration and extent of leukocytosis. Conclusions: These findings demonstrate the association of severe fever with further increase in energy expenditure and muscle protein catabolism in otherwise hypermetabolic burned children. This suggests a possible metabolic benefit in attenuating fever in such patients.