Measured energy expenditure in severe head trauma

Metabolic profiles of 20 patients admitted to the Conemaugh Valley Memorial Hospital Trauma Unit from July 1987 through June 1988 with Glasgow Coma Scale Scores of 7 or less were retrospectively reviewed. Analysis of Injury Severity Scale (ISS) determinations indicated that all patients had major closed head injury, and associated injuries were minor in nature. No significant co-morbid disease states were present in this patient population. All patients required mechanical ventilatory support, and within 48 hours of admission measurements of oxygen consumption (VO2), carbon dioxide production (VCO2) and respiratory quotient (VCO2/VO2) were made using a Beckman Metabolic Measurement Cart which employs indirect closed calorimetry to assess resting energy expenditure (REE). When predicted values of REE and VO2 (derived from the Harris-Benedict equation) were compared to actual measured data, the percentage increase over predicted was 160 +/- 37 (p less than 0.005) and 166 +/- 43 (p less than 0.005), respectively. Based on these observations it is evident that patients with severe head trauma are physiologically in an early hypermetabolic state, and that values of REE derived from standard formula are grossly inaccurate, leading to inadequate nutritional support.