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Updated: Sep 28, 2026
Assessment of Child Anthropometry in a Large Epidemiologic Study
Published on: February 2, 2017
Serial measurements of energy expenditure in critically ill children: useful in optimizing nutritional therapy?
Gijs de Klerk1, Wim C J Hop, Matthijs de Hoog
1Department of Pediatrics, Division of Pediatric Intensive Care, Erasmus University Rotterdam, PO Box 2060, 3000 CB Rotterdam, The Netherlands.
Insights
Mechanically ventilated children show variable total daily energy expenditure (TDEE), but individual needs are consistent. Optimal nutrition therapy involves 1.4x TDEE with specific macronutrient ratios and protein intake for better energy balance.
Area of Science:
- Pediatric critical care medicine
- Clinical nutrition
- Metabolic monitoring
Background:
- Accurate assessment of energy expenditure is crucial for optimizing nutritional support in critically ill children.
- Mechanically ventilated children often have unique metabolic demands that require precise monitoring.
Purpose of the Study:
- To investigate the variability of total daily energy expenditure (TDEE) and respiratory quotient (RQ) in mechanically ventilated children.
- To correlate energy balance with TDEE and RQ to guide nutritional therapy adjustments.
Main Methods:
- Serial measurements of TDEE and RQ using indirect calorimetry in 18 mechanically ventilated children.
- Recording daily caloric intake and analyzing 24-hour urine for nitrogen excretion.
- Calculating macronutrient-specific RQ (RQ(macr)) to assess substrate utilization.
Main Results:
- Significant inter-individual variability in TDEE (40-64 kcal/kg) but low intra-individual variation (<10% CV in 83% of patients).
- Children with positive cumulative energy balance exhibited higher RQ (0.89) compared to those with negative balance (0.84).
- Optimal caloric intake determined as 1.4x TDEE (60% carbohydrates, 40% fat) and protein intake as 1.9 g/kg.
Conclusions:
- A single TDEE measurement can reliably estimate daily energy needs for most mechanically ventilated children.
- RQ is influenced by energy intake relative to TDEE and cumulative energy status.
- Established optimal caloric and protein intake guidelines can improve nutritional therapy in this population.
Objectives:
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.