Feeding‐Induced Changes in Energy Expenditure in Children With Cystic Fibrosis

Seven children with cystic fibrosis (aged 7 to 12 years) were studied in the fasted and fed states. Using a primed, constant, intravenous infusion of NaH 13 CO 3 , the rate of appearance of CO 2 (RaCO 2 ) was estimated. Net CO 2 excretion (VCO 2 ) was also measured. Energy expenditure was calculated using the food quotient. RaCO 2 (mean ± SD) (μmol·kg −1 ·min −1 ) in the fasted and fed states (297 ± 59 and 359 ± 67) was 117% and 105% of VCO 2 (259 ±48 and 352 ± 72). Feeding induced a 23% and a 37% increase in RaCO 2 and VCO 2 , respectively, and respective 19% and 33% increases in energy expenditure ( p <.05). Measurement of CO 2 production by isotopic dilution is a useful index of group changes in energy expenditure, including those induced by feeding. ( Journal of Parenteral and Enteral Nutrition 18: 497–502, 1994)