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Resting energy expenditure and nitrogen balance in critically ill pediatric patients on mechanical ventilation
J A Coss-Bu1, L S Jefferson, D Walding
1Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA. jcossbu@msmailpo2.is5.tch.tmc.edu
Insights
Critically ill children exhibit hypermetabolism, with resting energy expenditure significantly higher than expected. Nutritional support needs careful monitoring, as nitrogen balance correlates with intake and age, not illness severity.
Area of Science:
- Pediatric critical care medicine
- Clinical nutrition
- Metabolic research
Background:
- Nutritional support is crucial for critically ill children, who have variable energy and nitrogen needs.
- Factors like sepsis, trauma, and postsurgical states influence metabolic demands.
- Understanding these needs is vital for optimizing patient outcomes.
Purpose of the Study:
- To investigate the relationship between age, illness severity, and mechanical ventilation with resting energy expenditure (REE) and nitrogen balance in critically ill children.
- To determine the protein requirements for this patient population.
- To assess the degree of hypermetabolism in pediatric critical illness.
Main Methods:
- Nineteen critically ill children receiving total parenteral nutrition (TPN) were studied.
- Resting energy expenditure (REE) was measured using indirect calorimetry.
- Illness severity was assessed using Pediatric Risk of Mortality (PRISM) and Therapeutic Intervention Scoring System (TISS) scores; nitrogen balance was determined via urinary nitrogen measurements.
Main Results:
- Critically ill children were hypermetabolic, with REE 48% higher than expected.
- Nitrogen balance was negatively correlated with caloric and protein intake, urinary nitrogen, and age.
- No significant correlation was found between nitrogen balance and illness severity scores or ventilatory parameters.
Conclusions:
- Critically ill children demonstrate significant hypermetabolism.
- Protein requirements are estimated at approximately 2.8 g/kg/day.
- Nitrogen balance is influenced by nutritional intake and patient age, highlighting the importance of tailored nutritional strategies.
Abstract:
Nutritional support is important in critically ill patients, with variable energy and nitrogen requirements (e.g., sepsis, trauma, postsurgical state) in this population. This study investigates how age, severity of illness, and mechanical ventilation are related to resting energy expenditure (REE) and nitrogen balance. Nineteen critically ill children (mean age, 8 +/- 6 [SD] y and range 0.4-17.0 y) receiving total parenteral nutrition (TPN) were enrolled. We used indirect calorimetry to measure REE. Expected energy requirements (EER) were obtained from Talbot tables. Pediatric Risk of Mortality (PRISM) and Therapeutic Intervention Scoring System (TISS) score were calculated. Total urinary nitrogen was measured using the Kjeldahl method. PRISM and TISS scores were 9 +/- 5 and 31 +/- 6 points, respectively. REE was 62 +/- 25 kcal.kg-1.d-1, EER was 42 +/- 11 kcal.kg-1. d-1, and caloric intake was 49 +/- 22 kcal.kg-1.d-1. Nitrogen intake was 279 +/- 125 mg.kg-1.d-1, total urinary nitrogen was 324 +/- 133 mg.kg-1.d-1, and nitrogen balance was -120 +/- 153 mg.kg-1.d-1. The protein requirement in this population was approximately 2.8 g.kg-1.d-1. These critically ill children were hypermetabolic, with REE 48% higher (20 kcal.kg-1.d-1) than expected. Nitrogen balance significantly correlated with caloric and protein intake, urinary nitrogen, and age, but not with severity of illness scores or ventilatory parameters.