What is the appropriate caloric requirement for a 6‑year‑old, 20‑kg child on mechanical ventilation?

Caloric Requirements for a 6-Year-Old Ventilated Child (20 kg)

A 6-year-old, 20 kg child on mechanical ventilation requires approximately 1,100-1,160 kcal/day (55-58 kcal/kg/day) based on measured resting energy expenditure in critically ill ventilated children.

Evidence-Based Caloric Targets

Acute Phase of Critical Illness

• During the first week of mechanical ventilation, target 70% of resting energy expenditure (REE), which equals approximately 770-812 kcal/day (38-40 kcal/kg/day) for this child, gradually progressing to 80-100% of energy expenditure 1
• The hypocaloric approach during acute phase prevents overfeeding while endogenous energy production provides the majority of requirements 1

Stable/Recovery Phase

• After the acute phase, provide 55-58 kcal/kg/day (1,100-1,160 kcal/day total) to equilibrate energy balance based on measured REE in ventilated critically ill children 2
• For catch-up growth during recovery, increase to approximately 1.3 times REE, which equals 71-75 kcal/kg/day (1,420-1,500 kcal/day total) 1

Critical Considerations for This Patient

Why Standard Equations Fail

• Predictive equations (Schofield, Harris-Benedict, WHO) are unreliable in ventilated critically ill children, with biases ranging from 200-1000 kcal/day and poor precision especially in younger children 3, 4, 5
• Even equations specifically developed for critically ill children (White, Meyer, Mehta) show unacceptable bias and may lead to significant underfeeding or overfeeding 3
• Standard prediction equations lack agreement with measured energy expenditure in individual patients despite good correlation at the population level 4

Measured vs. Predicted Energy Needs

• Measured REE in ventilated critically ill children averages 55 kcal/kg/day, which is substantially lower than traditional estimates 2
• There is considerable variability between children (range 17-66 kcal/kg/day), but variation within each child over time is small 6
• Indirect calorimetry is the gold standard when available, as it reveals that approximately 61% of ventilated children are overfed when using predictive equations 6

Practical Algorithm for Energy Delivery

If Indirect Calorimetry Available:

1. Measure REE and provide 70% during first week (approximately 770-812 kcal/day) 1
2. Progress to 100% of measured REE after acute phase (approximately 1,100 kcal/day) 1
3. Add 30% for catch-up growth during recovery (approximately 1,420 kcal/day) 1

If Indirect Calorimetry NOT Available:

1. Start with 55 kcal/kg/day (1,100 kcal/day) as baseline estimate 2
2. Monitor for signs of overfeeding: hyperglycemia, elevated respiratory quotient, difficulty weaning from ventilator 6
3. Monitor for signs of underfeeding: negative nitrogen balance, poor wound healing, failure to wean 4

Protein Requirements

Provide 1.5 g/kg/day of protein (30 g/day total) to achieve nitrogen equilibrium in this age group 2

• This is higher than Dietary Reference Intakes for healthy children but necessary due to elevated total urinary nitrogen (0.20 g/kg/day) in critically ill ventilated children 2
• Protein requirements are more consistent across critically ill children than energy requirements 2

Common Pitfalls to Avoid

Overfeeding Risk

• Overfeeding occurred in 60.5% of measurement days in one study, emphasizing the danger of using standard equations 6
• Overfeeding increases CO2 production, prolongs mechanical ventilation, and may increase length of stay 6, 3
• Fasting for procedures was the most frequent barrier to nutrition delivery, leading to compensatory overfeeding attempts 6

Underfeeding Risk

• Underfeeding occurred in 21.2% of measurement days, leading to negative nitrogen balance and impaired recovery 6
• Caloric intake/measured energy expenditure ratio must be ≥1.4 to achieve positive nitrogen balance 4

Monitoring Strategy

• Respiratory quotient has poor sensitivity (21-27%) for detecting underfeeding or overfeeding and should not be relied upon alone 6
• Daily assessment of nitrogen balance combined with energy expenditure measurement provides the most accurate nutritional monitoring 4