Measured energy expenditure in critically ill infants and young children.

Technological limitations have impeded accurate energy expenditure assessment in critically ill infants and young children. Instead, a predicted energy expenditure (PEE) is derived based on weight, heat loss, activity, growth requirements, and degree of stress. This study compared actual measured energy expenditure (MEE) with conventional predicted values in 20 critically ill infants and children using a validated metabolic cart designed for use in this age group. All patients were studied either within 4 days of major surgery or during an acute disease process necessitating intensive care. All were severely stressed clinically and were studied while mechanically ventilated in a temperature-controlled environment. The study interval ranged from 1 to 12 hr and averaged 4 hr after a stabilization period of 30 min. The mean MEE was significantly lower than the mean PEE (52.2 +/- 16 kcal/kg/day vs 101.8 +/- 17 kcal/kg/day, P less than 0.001) with a mean MEE/PEE of 52.6 +/- 17% (range 26 to 92%). In a subgroup of 7 paralyzed patients, the mean MEE was significantly lower than in the 13 nonparalyzed patients when compared with PEE and predicted basal metabolic rate (PBMR). The coefficient of variance, conventionally recognized to be approximately 15% for PEE, averaged 6.35% for MEE in this study. These data indicate that if PEE is used as the sole guide for caloric repletion in the stressed infant or child, these patients will be substantially overfed.