Reducing the time period of steady state does not affect the accuracy of energy expenditure measurements by indirect calorimetry.
Achievement of steady state during indirect calorimetry measurements of resting energy expenditure (REE) is necessary to reduce error and ensure accuracy in the measurement. Steady state is often defined as 5 consecutive min (5-min SS) during which oxygen consumption and carbon dioxide production vary by +/-10%. These criteria, however, are stringent and often difficult to satisfy. This study aimed to assess whether reducing the time period for steady state (4-min SS or 3-min SS) produced measurements of REE that were significantly different from 5-min SS. REE was measured with the use of open-circuit indirect calorimetry in 39 subjects, of whom only 21 (54%) met the 5-min SS criteria. In these 21 subjects, median biases in REE between 5-min SS and 4-min SS and between 5-min SS and 3-min SS were 0.1 and 0.01%, respectively. For individuals, 4-min SS measured REE within a clinically acceptable range of +/-2% of 5-min SS, whereas 3-min SS measured REE within a range of -2-3% of 5-min SS. Harris-Benedict prediction equations estimated REE for individuals within +/-20-30% of 5-min SS. Reducing the time period of steady state to 4 min produced measurements of REE for individuals that were within clinically acceptable, predetermined limits. The limits of agreement for 3-min SS fell outside the predefined limits of +/-2%; however, both 4-min SS and 3-min SS criteria greatly increased the proportion of subjects who satisfied steady state within smaller limits than would be achieved if relying on prediction equations.
Reeves
Marina M
MM
Centre for Research in Cancer Control, Queensland Cancer Fund, Queensland 4059, Australia. MReeves@qldcancer.com.au
Davies
Peter S W
PS
Bauer
Judith
J
Battistutta
Diana
D
D000368:Aged; D015982:Bias; D001827:Body Height / Q000502:physiology; D002153:Calorimetry, Indirect / Q000379:methods* / Q000592:standards; D002245:Carbon Dioxide / Q000097:blood; D004734:Energy Metabolism / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000378:metabolism; D010100:Oxygen / Q000097:blood; D011659:Pulmonary Gas Exchange / Q000502:physiology; D015203:Reproducibility of Results; D013997:Time Factors
D002245:Carbon Dioxide; D010100:Oxygen