Indirect calorimetry: a tool to adjust energy expenditure in very low birth weight infants.

OBJECTIVE To determine the resting metabolic rate in very low birth weight infants through indirect calorimetry. METHODS Cross-sectional study including 29 clinically stable very low birth weight infants receiving an enteral diet > 100 kcal/kg/day. Malnutrition was defined as weight-for-age z score < or = - 2 SD. Resting energy expenditure was measured using open circuit indirect calorimetry. RESULTS At the time of the examination, mean weight was 1,564+/-393 g and corrected gestational age was 35+/-3 weeks. Malnutrition was diagnosed in 62.1% of the preterm infants. The mean resting metabolic rate was 57.01+/-7.76 kcal/kg/day. CONCLUSION Since resting energy expenditure is the main caloric component of total energy expenditure, the high resting metabolic rate observed may have a strong impact on the development of malnutrition during hospitalization.