Am J Perinatol 2017; 34(05): 493-498
DOI: 10.1055/s-0036-1593476
Original Article
Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

Effect of Body Position on Energy Expenditure of Preterm Infants as Determined by Simultaneous Direct and Indirect Calorimetry

Edward F. Bell
1  Department of Pediatrics, University of Iowa, Iowa City, Iowa
Karen J. Johnson
1  Department of Pediatrics, University of Iowa, Iowa City, Iowa
Edwin L. Dove
2  Department of Biomedical Engineering, University of Iowa, Iowa City, Iowa
› Author Affiliations
Further Information

Publication History

23 June 2016

31 August 2016

Publication Date:
07 October 2016 (online)


Background Indirect calorimetry is the standard method for estimating energy expenditure in clinical research. Few studies have evaluated indirect calorimetry in infants by comparing it with simultaneous direct calorimetry. Our purpose was (1) to compare the energy expenditure of preterm infants determined by these two methods, direct calorimetry and indirect calorimetry; and (2) to examine the effect of body position, supine or prone, on energy expenditure.

Study Design We measured energy expenditure by simultaneous direct (heat loss by gradient-layer calorimeter corrected for heat storage) and indirect calorimetry (whole-body oxygen consumption and carbon dioxide production) in 15 growing preterm infants during two consecutive interfeeding intervals, once in the supine position and once in the prone position.

Results The mean energy expenditure for all measurements in both positions did not differ significantly by the method used: 2.82 (standard deviation [SD] 0.42) kcal/kg/h by direct calorimetry and 2.78 (SD 0.48) kcal/kg/h by indirect calorimetry. The energy expenditure was significantly lower, by 10%, in the prone than in the supine position, whether examined by direct calorimetry (2.67 vs. 2.97 kcal/kg/h, p < 0.001) or indirect calorimetry (2.64 vs. 2.92 kcal/kg/h, p = 0.017).

Conclusion Direct calorimetry and indirect calorimetry gave similar estimates of energy expenditure. Energy expenditure was 10% lower in the prone position than in the supine position.