title: Minimum Time to Achieve the Steady State and Optimum Abbreviated Period to Estimate the Resting Energy Expenditure by Indirect Calorimetry in Healthy Young Adults.
abstract: BACKGROUND
  The optimum abbreviated period for measurement by indirect calorimetry (IC) to estimate the resting energy expenditure (REE), including the acclimation period, in healthy individuals has not been established. This study aimed to determine the acclimation time required to achieve the REE steady state during a 30-minute IC measurement and to define the optimum abbreviated measurement period in the steady state to estimate the REE in healthy young adults.
  
  
  METHODS
  Thirty-nine volunteers (27 men and 12 women; age, 18-31 years) were recruited. The REE was obtained by IC over 30 minutes. Friedman's test was used to compare the coefficient of variation (CV%) among all 5-minute intervals (REE5). To compare the REE values obtained during the first REE5 interval in the steady state with the REE average values of the subsequent measurements, Student paired t test, linear regression, and Bland-Altman test were used.
  
  
  RESULTS
  The CV% of the first REE5 (mean ± standard deviation: 19.9% ± 13.2%) was significantly higher (P < .0001) than that of all other REE5 (second REE5: 7.4% ± 3.8%; third: 7.8% ± 5.2%; fourth: 7.1% ± 3.9%; fifth: 8.0% ± 5.7%; sixth: 8.0% ± 4.5%). No significant difference was found between the second REE5 and the REE average values of the last 20 minutes. The second REE5 explained 90% of the REE average of the last 20 minutes, with the 95% limits of agreement by the Bland-Altman test ranging from -142.92 to 150.44 kcal/d.
  
  
  CONCLUSIONS
  Ten minutes can be used as an abbreviated alternative for IC measurements in healthy young adults, and values of the first 5-minute interval should be discarded.
authors.affiliation: Growth and Development Laboratory, Center for Investigation in Pediatrics (CIPED), School of Medical Sciences (FCM), University of Campinas (UNICAMP), Campinas-SP, Brazil borges02@hotmail.com.
authors.forename: Juliano H
authors.initials: JH
authors.lastname: Borges
authors.affiliation: Growth and Development Laboratory, Center for Investigation in Pediatrics (CIPED), School of Medical Sciences (FCM), University of Campinas (UNICAMP), Campinas-SP, Brazil.
authors.forename: Raquel D
authors.initials: RD
authors.lastname: Langer
authors.affiliation: Growth and Development Laboratory, Center for Investigation in Pediatrics (CIPED), School of Medical Sciences (FCM), University of Campinas (UNICAMP), Campinas-SP, Brazil.
authors.forename: Vagner X
authors.initials: VX
authors.lastname: Cirolini
authors.affiliation: Growth and Development Laboratory, Center for Investigation in Pediatrics (CIPED), School of Medical Sciences (FCM), University of Campinas (UNICAMP), Campinas-SP, Brazil.
authors.forename: Mauro A
authors.initials: MA
authors.lastname: Páscoa
authors.affiliation: Growth and Development Laboratory, Center for Investigation in Pediatrics (CIPED), School of Medical Sciences (FCM), University of Campinas (UNICAMP), Campinas-SP, Brazil Department of Pediatrics, FCM, UNICAMP, Campinas-SP, Brazil.
authors.forename: Gil
authors.initials: G
authors.lastname: Guerra-Júnior
authors.affiliation: Growth and Development Laboratory, Center for Investigation in Pediatrics (CIPED), School of Medical Sciences (FCM), University of Campinas (UNICAMP), Campinas-SP, Brazil.
authors.forename: Ezequiel M
authors.initials: EM
authors.lastname: Gonçalves
mesh_terms: D000293:Adolescent; D000328:Adult; D001481:Basal Metabolism / Q000502:physiology*; D002153:Calorimetry, Indirect / Q000379:methods / Q000706:statistics & numerical data; D004734:Energy Metabolism; D005260:Female; D006801:Humans; D008297:Male; D012016:Reference Values; D015203:Reproducibility of Results; D013997:Time Factors; D055815:Young Adult
keywords: energy metabolism; indirect calorimetry; mechanical ventilation; nutrition; resting energy expenditure