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Comparison of measured and predicted energy expenditure in mechanically ventilated children
J J Verhoeven1, J A Hazelzet, E van der Voort
1Department of Pediatrics, Sophia Children's Hospital, University Hospital Rotterdam, The Netherlands.
Insights
Indirect calorimetry is essential for determining accurate energy needs in mechanically ventilated pediatric patients. Standard prediction equations are unreliable, necessitating individualized assessments for optimal nutritional support.
Area of Science:
- Pediatric critical care medicine
- Clinical nutrition
- Metabolic research
Background:
- Accurate energy assessment is vital for critically ill pediatric patients.
- Mechanically ventilated children often have altered metabolic states.
- Existing predictive equations may not reflect actual energy expenditure.
Purpose of the Study:
- To measure energy requirements in mechanically ventilated pediatric patients using indirect calorimetry.
- To compare measured energy expenditure with predicted metabolic rates.
- To evaluate the adequacy of nutritional support based on nitrogen balance.
Main Methods:
- Indirect calorimetry was used to measure energy expenditure in 50 mechanically ventilated children.
- Caloric intake was monitored daily for all participants.
- Urinary nitrogen excretion was analyzed in a subset of patients to assess nitrogen balance.
Main Results:
- A strong correlation was observed between measured total energy expenditure (mTEE) and predicted basal metabolic rate (pBMR) (r=0.93, p<0.001).
- However, Bland-Altman analysis revealed significant discrepancies between individual mTEE and pBMR values.
- Patients with positive nitrogen balance had a higher caloric intake/mTEE ratio (1.4 ± 0.07) than those with negative balance (0.8 ± 0.1; p<0.001).
Conclusions:
- Standard predictive equations are inadequate for determining the energy needs of critically ill, mechanically ventilated children.
- Individualized measurement of energy expenditure via indirect calorimetry is crucial.
- Combining indirect calorimetry with nitrogen balance assessment ensures appropriate nutritional support.
Objective:
To determine the energy requirements in mechanically ventilated pediatric patients using indirect calorimetry and to compare the results with the predicted metabolic rate.
Design:
In 50 mechanically ventilated children with a moderate severity of illness, energy expenditure was measured by indirect calorimetry. Daily caloric intake was recorded for all patients. Total urinary nitrogen excretion was determined in 31 patients.
Results:
Although there was a close correlation between the measured total energy expenditure (mTEE) and the predicted basal metabolic rate (pBMR) (r = 0.93, p < 0.001), Bland-Altman analysis showed lack of agreement between individual mTEE and pBMR values. The ratio of caloric intake/mTEE was significantly higher in the patients with a positive nitrogen balance (1.4 +/- 0.07) compared with those with a negative nitrogen balance (0.8 +/- 0.1; p < 0.001).
Conclusions:
Standard prediction equations are not appropriate to calculate the energy needs of critically ill, mechanically ventilated children. Individual measurements of energy expenditure and respiratory quotient by means of indirect calorimetry in combination with nitrogen balance are necessary for matching adequate nutritional support.