Metabolic rate in febrile infants

Energy cost of fever in children on total parenteral nutrition

The aim of the study was to measure the changes in energy expenditure (EE) and respiratory quotient (RQ) induced by fever in children receiving total parenteral nutrition (TPN). Ten children aged 1-16 years (weight for height: 104.5 +/- 13%) were included. They underwent two EE recordings of 3 h duration using indirect calorimetry, during a febrile (38.9 +/- 0.5 degrees C) and afebrile conditions, after parameters (nutritional intake, ambient temperature) being equal. The EE, (febrile phase) was significantly higher than the EE(2) (afebrile) (2.13 +/- 0.48 vs 1.78 +/- 0.42 kcal/kg/h; P < 0.01). Increase in EE was significantly correlated with body temperature (r = 0.92, P < 0.001). The slope of the regression line indicates an increase of 16.2% in EE per degree of fever. By dividing the individual increase in EE by the individual increase in temperature, the energy expenditure during fever is 11.3% per unit rise ( degrees C). During the febrile phase urinary nitrogen excretion was significantly higher (280 +/- 90 vs 210 +/- 70 mg/kg fat free mass/day, P < 0.02). The RQ during the febrile phase (0.90 +/- 0.13) did not differ significantly from mean RQ during the afebrile phase (0.95 +/- 0.07). Fever due to infection or inflammatory process is partly responsible for an hypermetabolic state including increased EE.

Effect of infection on energy requirements of infants and children

This is a brief review of the effects of infection and other forms of stress on the energy needs of infants and young children. The results of studies estimating energy expenditure in infants and young children during illness and convalescence were evaluated. Expectations that energy expenditure is influenced by the severity of illness, nutritional status, the nature of the illness, the presence and intensity of ‘catch-up growth,’ and the stage of convalescence are generally supported by the literature. The qualitative or quantitative nature of responses, however, are not uniform for diverse illnesses in children in diverse planes of nutritional adequacy.

Energy metabolism in infants with congenital heart disease

Failure to thrive is common in children with congenital heart disease and influences the metabolic response to injury and outcome after corrective cardiac surgery. Energy imbalance is a major contributing factor. However, the published literature is difficult to interpret as studies generally involve small patient numbers with a diverse range of types and severity of cardiac lesions and genetic and/or prenatal factors. The age and time of corrective surgery affects the potential for nutritional recovery. Although the immediate postoperative period is characterized by a hypermetabolic state, low total and resting energy expenditure are reported within 24 h of surgery. After 5 d, resting energy expenditure returns to preoperative levels. Significant improvements in weight and growth occur within months after corrective surgery. However, limited postoperative recovery in nutritional status and growth occurs in infants with a low birth weight, intellectual deficit, or residual malformation. Further studies are needed to inform the timing of corrective cardiac surgery to maximize nutritional outcomes and to identify those infants who may benefit from aggressive preoperative nutrition support.

The pragmatics of feeding the pediatric patient with acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) represents the ultimate pulmonary response to a wide range of injuries, from septicemia to trauma. Optimal nutrition is vital to enhancing oxygen delivery, supporting adequate cardiac contractility and respiratory musculature, eliminating fluid and electrolyte imbalances, and supporting the proinflammatory response. Research is providing a better understanding of nutrients that specifically address the complex physiologic changes in ARDS. This article highlights the pathophysiology of ARDS as it relates to nutrition, relevant nutritional assessment, and important enteral and parenteral considerations for the pediatric patient who has ARDS.

Estimation of the energy cost of physical activity in infancy

OBJECTIVE

To estimate physical activity energy expenditure (AEE) in groups of free living infants in the first year of life.

DESIGN

Mixed longitudinal study of 124 healthy infants, using 232 estimations of AEE made between 1.5 and 12 months. Infants studied at more than one time point were treated as new cross sectional data points. Total energy expenditure and body composition were estimated using doubly labelled water. Sleeping metabolic rate was predicted from weight.

RESULTS

AEE increased from 5% of energy intake at 1.5 months to 34% at 12 months. Growth costs declined by 90%, but metabolisable intake by only 20%, over the same period.

CONCLUSIONS

Energy is increasingly diverted from growth to activity during infancy. Values for AEE may aid in estimating energy requirements of groups factorially. Further work is required, however, on individual variability in AEE, and on the effects of disease, hospitalisation, surgery, and malnutrition.