Measuring resting energy expenditure in clinical practice

Exploration of the Contribution of Biobehavioral Variables to the Energy Expenditure of Preterm Infants

Variation in energy expended by preterm infants may be due to infant maturity and history of resolved acute lung disease (respiratory distress syndrome [RDS]) as well as growth, caloric intake, and activity. Indirect calorimetry was used in this exploratory, short-term longitudinal study to estimate energy expenditure (EE) from measures of inspired and expired O2 and CO2 .The sample included 35 assessments for 10 preterm infants (5 with and 5 without RDS history). Lung disease history (resolved RDS, no RDS diagnosis), weight gain (g/d) from the day on which birth weight had been regained to the study day, mean activity level, the number of the assessment (1 6), and the interaction of lung disease history and time were included in a linear mixed model for repeated measures. Time was an index of postconceptional and postnatal age; all 3 were highly correlated. Because of high correlation with weight gain, caloric intake was not included in the analytic model. Lung disease history, mean activity level, and time were significant contributors to EE. A more precise measure of medical status than absence or presence of lung disease history, evenly spaced repetitions of EE assessment, and exploration of contexts in which the infants exhibit a higher activity level are needed in a replication study with a larger sample.

Autonomic nervous system balance in children and adolescents with craniopharyngioma and hypothalamic obesity

OBJECTIVE

Dysregulation of the autonomic nervous system is thought to be involved in craniopharyngioma-related hypothalamic obesity (CRHO). Increased parasympathetic activity and decreased sympathetic activity have been suggested. We aimed to study autonomic activity using heart rate variability (HRV) and biochemical measures in youth with CRHO compared with controls and to explore relationships between obesity and autonomic indices.

DESIGN

A cross-sectional study of 16 youth with CRHO and 16 controls matched for sex, age, and BMI.

METHODS

Anthropometrics, fasting blood-work, resting energy expenditure (REE), 24-h HRV, and 24-h urine catecholamines were assessed. Quality of life, sleepiness, and autonomic symptoms were evaluated. Power spectral analysis of the HRV was performed.

RESULTS

HRV power spectral analysis parameters of both parasympathetic activity (mean high frequency (HF (ms(2))) 611±504 vs 459±336, P=0.325) and sympathetic activity (median low frequency/HF 1.62 (1.37, 2.41) vs 1.89 (1.44, 2.99), P=0.650) did not differ between the groups. Parasympathetic activity negatively correlated with central adiposity in both groups (r=-0.53, P=0.034 and r=-0.54, P=0.029) and sympathetic activity positively correlated with central adiposity in CRHO (r=0.51, P=0.043). Youth with CRHO had significantly lower REE; lower health and activity scores in the quality of life questionnaires, and higher sleepiness scores.

CONCLUSIONS

Autonomic activity was similar in CRHO and control subjects. The degree of central adiposity correlated negatively with parasympathetic activity and positively with sympathetic activity in children with CRHO. These results provide a new perspective regarding autonomic balance in this unique patient population.

Insulin sensitivity and secretion in children and adolescents with hypothalamic obesity following treatment for craniopharyngioma

BACKGROUND

Craniopharyngioma (CP), a tumour occurring in the hypothalamic-pituitary area, results in morbid obesity in 25-60% of affected children. It has been suggested that abnormalities of insulin secretion and/or insulin action due to hypothalamic injury may be associated with weight gain and the metabolic syndrome in this population.

AIM

To evaluate: (i) insulin secretion (IS) and insulin sensitivity (Si); (ii) features of the metabolic syndrome (MS) and (iii) factors involved in risk for diabetes and heart disease in obese youth treated for CP.

METHODS

Obese subjects treated for CP were compared to BMI-matched control subjects. All subjects underwent anthropometric, blood pressure, resting energy expenditure and body fat assessment. Cholesterol and inflammatory markers, oral glucose tolerance test (OGTT) and frequent sampling intravenous glucose tolerance test (FSIGT), with calculation of IS and Si, were performed.

RESULTS

Fifteen CP subjects and 15 controls (C) were studied. There were no differences between CP and C for age, gender, BMI or pubertal status. MS was present in 10/15 CP and 3/15 C (P = 0.03), including impaired glucose tolerance (IGT) in 6/15 CP and 0/15 C (P = 0.02). Measures of IS, including first and second phase IS, and insulin area-under-the-curve (AUC(ins)) during OGTT, were significantly higher in CP. Si, measured by frequent sampled intravenous glucose tolerance test (Si-FSIGT), was significantly lower in CP subjects (0.96 +/- 0.34 vs. 1.67 +/- 0.7; P = 0.01). AUC(ins) was negatively correlated with Si-FSIGT (r = -0.62; P = 0.003).

CONCLUSION

Children with CP and hypothalamic obesity have more features of MS, increased IS and IGT prevalence and lower Si compared with BMI-matched controls.

Is it necessary to measure resting energy expenditure in clinical practice in children?

We compared measured resting energy expenditure (MREE) and predicted resting energy expenditure (PREE) in 398 chronically ill children and found a wide variability for %MREE/PREE (standard deviation +/- 27.2). Bland-Altman analysis also suggested poor agreement between MREE and PREE (mean bias, 43.2 kcal; range, -645 to 1118.1 kcal). Our findings suggest that resting energy expenditure should be measured in chronically ill children.

Determining the least time required for measuring energy expenditure in premature neonates

OBJECTIVE

To compare O2 consumption, CO2 production, respiratory quotient and resting metabolic rate in premature neonates measured for 5 and 10 min steady-state periods and 15 and 20 min non-steady-state periods versus a 2-h measurement period.

METHODS

A prospective study with neonates evaluated by indirect calorimetry. The measurements from the 5, 10, 15, and 20 min periods were taken based on the printout data from the IC monitor at an interval of 1 h before the beginning feeding and were contained in the 2-h measurement. The 5- and 10-min measurements followed the steady-state criterion.

RESULTS

We evaluated 35 premature neonates appropriate for gestational age (born at 28-34 weeks' gestation). Mean age was 20 days+/-9 (median 14 days) and mean weight was 1530+/-270 g (median 1510 g). There was no statistically significant difference between mean VO2, VCO2, respiratory quotient and energy expenditure at 5, 10, 15, and 20 min and 2 h.

CONCLUSIONS

The 5 and 10 min steady-state measurements or a measurement of more than 15 min without reaching steady state produce results similar to those of 2 h measurements.

Energy Costs of Physical Activities in Children and Adolescents

PURPOSE

The primary aim was to determine the energy expenditure (EE: kcal.kg(-1).h(-1)) in terms of caloric cost and metabolic equivalents of activities commonly performed by children and adolescents. Secondary aims were to determine at what age and pubertal developmental stage values approach those of adults.

METHODS

In this descriptive study, 295 volunteer youth 8-18 yr of age completed 18 common physical activities (including rest) while EE was measured continuously with a portable metabolic system. Three sets of activities were assigned in random order for each subject. Activities ranged from television viewing and video game play to running and rope skipping. Pubertal development was estimated from a self-report questionnaire.

RESULTS

At rest, VO(2) and EE were highest in the youngest children and decreased with advancing age and higher pubertal stage in both genders. The age-adjusted and puberty-adjusted energy expenditure values were generally lower than the compendium MET values for sedentary and moderate activities but were more varied for high-intensity activities. However, the ratio of activity EE to REE was comparable in children and adults.

CONCLUSIONS

Energy expenditure per kilogram of body mass at rest or during exercise is greater in children than adults and varies with pubertal status, thus using the definition of a MET in the compendium of physical activities without adjustment is inadequate for energy estimation in children, until a child reaches Tanner Stage 5. However, the ratio of activity EE to resting EE in children appears to be similar or slightly less than in the compendium, suggesting that the compendium MET increments used with our adjusted EE values more closely approximate the true EE of activities in children than present adult norms.

Energy requirements of children with cerebral palsy

Energy requirements of children and adolescents with cerebral palsy appear to be disease-specific and different from the current recommendations for healthy children, varying depending upon functional capacity, degree of mobility, severity of disease, and level of altered metabolism. Feeding problems are prevalent in many of these children, and can result in inadequate energy intake. Wasting of voluntary muscles, a common symptom of cerebral palsy, contributes to reduced resting energy needs; nevertheless, the location of the central nervous system lesion may also influence energy requirements. To guarantee individualized, accurate, and optimal energy recommendations for this population, resting energy expenditure should preferentially be measured by indirect calorimetry. Equations and formulae to predict healthy people's resting energy expenditure are available, but tend to overestimate these children's energy needs. Future studies should address the role of the central nervous system in regulating energy metabolism in this population. When adequately nourished, children and adolescents with cerebral palsy appear more tranquil and require decreased feeding time, which gives caregivers time to develop the child's functional independence and character. Understanding energy requirements of this population will provide caregivers and health professionals with guidelines for providing optimal nutritional status.

[Influence of energy expenditure on childhood obesity]

OBJECTIVES

To study differences in resting energy expenditure (REE) according to its determining factors (sex, weight, body fat mass, lean body mass) and in the oxidation of energy substrates in obese and non-obese children.

PATIENTS AND METHODS

We studied 71 children (39 obese and 32 non-obese) aged from 4.1 to 13.6 years. The male/female ratio was 34/37. Energy expenditure (EE) was measured by using open circuit indirect calorimetry. The oxidation of energy substrates was calculated from oxygen consumption, carbon dioxide production, and urinary nitrogen excretion from urea. Body composition was determined by anthropometry.

RESULTS

REE (kcal/day), adjusted for anthropometric parameters and body composition, was higher in boys than in girls. The absolute REE was significantly higher in obese than in non-obese children (1512.82 6 234.47 vs 1172.59 6 190.20) and was higher or the same when adjusted for its determinants. Compared with the non-obese group, the obese group presented a significantly higher percentage of fat oxidation (57.15 6 10.68 vs 51.08 6 13.61, p 5 0.04), a lower percentage of carbohydrate oxidation (30.10 6 9.85 vs 36.34 6 13.61, p 5 0.03) and a lower respiratory quotient (0.79 6 0.03 vs 0.82 6 0.04, p 5 0.02). No differences were found between male and female subjects in the percentages of carbohydrate, fat, and protein oxidation.

CONCLUSIONS

We obtained the followings conclusions: a) When adjusted for anthropometric measurements and body composition, REE was significantly higher in boys than in girls; b) REE was higher in obese than in non-obese children, after adjustment for lean body mass; and c) Compared with the control group, obese children presented a higher percentage of fat oxidation, a lower percentage of carbohydrate oxidation, and a lower respiratory quotient.

Basal metabolic rate in children with a solid tumour

OBJECTIVE

To study the level of and changes in basal metabolic rate (BMR) in children with a solid tumour at diagnosis and during treatment in order to provide a more accurate estimate of energy requirements for nutritional support.

DESIGN

An observational study.

SETTING

Tertiary care at the Centre for Paediatric Oncology, University Hospital Nijmegen.

SUBJECTS

Thirteen patients were recruited from a population of patients visiting the University Hospital Nijmegen for treatment. All patients asked to participate took part in and completed the study.

INTERVENTION

BMR was measured by indirect calorimetry, under stringent, standardised conditions, for 20 min and on three different occasions in all patients. Continuous breath gas analysis using a mouthpiece was performed. Weight, height and skinfold measurements were performed before each measurement.

MAIN OUTCOME MEASURES

BMR was expressed as percentage of the estimated reference value, according to the Schofield formulas based on age, weight and sex, and in kJ (kcal) per kg of fat-free mass.

RESULTS

At diagnosis, the BMR was higher than the estimated reference BMR in all patients and 44% of the patients were considered hypermetabolic. Mean BMR (as percentage of reference) was significantly increased (11.6% (s.d. 6.7%); P=0.001), but decreased during treatment in 12 of the 13 patients (mean decrease 12.7% (s.d. 3.9%); P<0.0001). Furthermore, a significant negative correlation (P=-0.67; P=0.01) was found between the change in BMR and tumour response.

CONCLUSIONS

These data suggest that the BMR of children with a solid tumour is increased at diagnosis and possibly during the first phase of oncologic treatment. This may be important when determining energy requirements for nutritional support.

Resting energy expenditure and prediction equations in young children with failure to thrive

OBJECTIVE

To compare predicted and measured resting energy expenditure (REE) in young children (birth to 3 years) with failure to thrive (FTT).

METHODS

REE (kcal/d) was measured by indirect calorimetry and compared with predicted REE from 3 sex and age group equations: World Health Organization (WHO), Schofield weight-based (SCH-WT), and Schofield weight- and height-based (SCH-WT-HT). The clinical characteristics associated with inaccuracy of predicted REE were examined.

RESULTS

Forty-five subjects (47% female) were evaluated. Their clinical characteristics (mean +/- SD) included age 1.2 +/- 0.7 years, length/height z score -2.1 +/- 1.3, weight z score -2.7 +/- 1.0, and measured REE 438 +/- 111 kcal/d. All prediction equations were within 10% accuracy <50% of the time. However, SCH-WT-HT did not significantly differ from measured REE (450 +/- 138 vs 438 +/- 111 kcal/d, P =.2) and was least likely to underestimate REE. Younger age and more severe growth failure (based on weight, length/height, or both) were associated with underestimation of REE by prediction equations.

CONCLUSION

REE should be measured in young infants and children with moderate to severe FTT when knowledge of caloric needs is required for optimal clinical care. The SCH-WT-HT equation was least likely to underestimate REE and is therefore preferred when REE cannot be measured in this group of children.

Energy expenditure and body composition in children with spastic quadriplegic cerebral palsy

OBJECTIVE

To determine the relationship between resting energy expenditure and body cell mass in a group of children with spastic quadriplegic cerebral palsy (SQCP) in comparison with a group of healthy volunteers.

SUBJECTS AND METHODS

Children with SQCP (n = 13) and healthy control subjects (n = 21) participated in the study. Resting energy expenditure (REE) by indirect calorimetry, as well as body composition measurements were obtained. Those included skinfold measurements, isotope dilution methods for total body water and extracellular water (2H2O or H2(18)O and NaBr, respectively), and bioelectrical impedance analysis. Intracellular water was calculated as total body water minus extracellular water.

RESULTS

Overall REE in children with SQCP was significantly less than in control subjects or from predicted World Health Organization equations. There was a poor correlation between REE and weight or height for children with SQCP and those for control subjects. Children with SQCP showed a higher variance and small improvement in the correlation between REE and lean body mass or intracellular water in comparison with control subjects. Nine of the thirteen children with SQCP had significantly reduced REE per unit of lean tissue or intracellular water. Furthermore, bioelectrical impedance analysis was validated against dilution methods as a suitable technique for measuring total body water (r2 = 0.90, r = 0.95) and extracellular water (r2 = 0.84, r = 0.92) in children with SQCP.

CONCLUSION

REE in children with SQCP is poorly correlated with body cell mass. We postulate that the central nervous system plays a crucial role in energy regulation. In children with SQCP, individual energy expenditure should be measured so that optimal nutritional status can be achieved. Bioelectrical impedance analysis can be used in this population to measure body water spaces.