Energy Expenditure in Young Adults and Newborns by Indirect Calorimetry

Hong, Jeong; Kwon, Young Min; Kim, Myoung Wook

Abstract

PURPOSE: Providing an adequate amount of energy is important in patients with depleted nutrition. Indirect calorimetry is a portable tool that can measure the resting energy expenditure, the respiratory quotient, and the ratio of substrate utilization. Another way of getting the energy expenditure is through the use of equations, and that has been a more common way to get the basal energy expenditure. However, there has been a controversy that the energy expenditures calculated from equations are not the same as the values measured by indirect calorimetry. METHODS: Our study was to clarify this difference in two different groups with different physical conditions and growth. One was a normal-adult group (n=18), and their energy expenditure was calculated using the Harris-Benedict equations. The other was a normal-newborn group (n=7), and their energy expenditure was calculated using the Schofield equations. Calculated values were compared with the resting energy expenditure from indirect calorimetry (Deltatrac Metabolic Monitor, Datex Inc. Finland). RESULTS: In the adults, the basal energy expenditure was 1703.3+/-100.2 kcal/d according to the Harris-Benedict equations, and the resting energy expenditure was 1701+/-289.6 kcal/d according to indirect calorimetry (p>0.1). VO2 was 245.7+/-42.8 ml/min, VCO2 was 210+33.4 ml/min, and RQ was 0.86+/-0.05. In the neonates, the basal energy expenditure was 184.1+/-15.1 kcal/d according to the Schofield equations, and the resting basal energy expenditure was 154.3+/-32.1 kcal/d (p<0.05). VO2 was 21.9+/-4.3 ml/min, VCO2 was 18.7+/-4.0 ml/min, and RQ was 0.85+/-0.02. The ratios of substrate utilization were 192.1+/-58.8 g/d (48.03+/-16.8%) for carbohydrates, 69.7 +/-35.6 g/d (37.8+/-17.2%) for fats, and 55.8+/-14.9 g/d (14.3+/-3.9%) for proteins in the adults. In the neonates, the ratios were 18.6+/-5.6 g/d (50.3+/-7.0%) for carbohydrates, 18.6+/-1.1 g/d (47.7+/-6.2%) for fats, and 1+/-0 g/d (3.0+/-0.73%) for proteins. CONCLUSION: The difference between the basal energy expenditure obtained from equations and the resting energy expenditure obtained from indirect calorimetry could be identified only in the neonate group, but not in the adult group. It is speculated that resting energy expenditure was more reliable than the basal energy expenditure in neonates. Indirect calorimetry canbe a useful tool to correct the errors in the values obtained from equations, and other parameters, such as the respiratory quotient and the ratio of substrate utilization, should be evaluated in nutritional support.