title: Serial measurements of energy expenditure in critically ill children: useful in optimizing nutritional therapy?
abstract: OBJECTIVE
  To determine the variation in total daily energy expenditure (TDEE) and respiratory quotient (RQ) in mechanically ventilated children and examine the relation to daily and cumulative energy balance toward optimizing nutritional therapy.
  
  
  METHODS
  Serial measurements of TDEE and RQ were performed in 18 patients (median age 16 months) with an indirect calorimeter during admission (total 69 TDEE measurements). Daily caloric intake was recorded, and after determination of the amount of carbohydrates and fat a RQ of these macronutrients (RQ(macr)) was obtained. Daily 24-h urine was analyzed for urinary nitrogen excretion.
  
  
  RESULTS
  There was a great variability in the median serial TDEE between children (40-64 kcal/kg), while the variation within individual children was small; the mean intraindividual coefficient of variation (CV) in daily measurements of TDEE was less than 10% in 15 of the 18 children (83%). On the last day of measurement 8 children with a positive cumulative energy balance (+98 kcal/kg) had a significantly higher RQ than 10 with a negative cumulative energy balance (-24 kcal/kg, 0.89 vs. 0.84). From the difference between RQ and RQ(macr) the optimal caloric intake was determined as 1.4x TDEE, divided into 60% carbohydrates and 40% fat. From the median nitrogen excretion of 33 samples (300 mg/kg per day, range 60-708) optimal daily protein intake was calculated as 1.9 g/kg (range 0.4-4.4).
  
  
  CONCLUSIONS
  For most children a single measurement of TDEE gave a good insight in the daily energy needs. RQ is strongly affected by the ratio energy intake/TDEE and by the cumulative energy balance. Optimal caloric intake was found to be 1.4x TDEE with a daily protein intake of 1.9 g/kg.
authors.affiliation: Department of Pediatrics, Division of Pediatric Intensive Care, Erasmus University Rotterdam, PO Box 2060, 3000 CB Rotterdam, The Netherlands.
authors.forename: Gijs
authors.initials: G
authors.lastname: de Klerk
authors.forename: Wim C J
authors.initials: WC
authors.lastname: Hop
authors.forename: Matthijs
authors.initials: M
authors.lastname: de Hoog
authors.forename: Koen F M
authors.initials: KF
authors.lastname: Joosten
mesh_terms: D002675:Child, Preschool; D016638:Critical Illness; D002149:Energy Intake; D004734:Energy Metabolism; D005260:Female; D006801:Humans; D007223:Infant; D015278:Intensive Care Units, Pediatric; D008297:Male; D009584:Nitrogen / Q000652:urine; D018529:Nutritional Support; D012121:Respiration, Artificial; D018709:Statistics, Nonparametric
chemical_list: D009584:Nitrogen