Longitudinal evaluation of energy expenditure in preterm infants with birth weight less than 1000 g

Abstract

The aim of the present study was to obtain serial values of O₂ consumption (V_{O2), CO2 production (VCO2) and energy expenditure (EE) in healthy but extremely-low-birth-weight infants (birth weight VO2 increased from 4·7 (SD 0·5) TO 9·1 (sd 1·0) ml/kg per min, VCO2 from 4·5 (sd 0·4) to 8·3 (SD 0·6) ml/kg per min and EE from 115 (sd 12) to 310 (sd 71) kJ/kg per d. The energy intake was always higher than EE, even at days 6 and 12. The RER decreased from 0·99 (sd 0·09) at day 12 to 0·91 (SD 0·05) at day 30. On all study days, there were highly significant positive correlations between energy intake and weight gain, EE and weight gain, and EE and energy intake (P<0·05). Multiple regression analysis showed that on most study days EE was more affected by energy intake than by weight gain. We conclude that in healthy preterm infants with birth weight <1000 g, EE increases by about 150 % in the first 5 weeks after birth, and that the EE values are related to energy intake and weight gain independent of postnatal age.}