title: Child-specific thoracic gas volume prediction equations for air-displacement plethysmography.
abstract: OBJECTIVE
  To develop child-specific thoracic gas volume (TGV) prediction equations for use in air-displacement plethysmography in 6- to 17-year-old children.
  
  
  METHODS
  Study 1 developed TGV prediction equations using anthropometric variables after completing a measured TGV and air-displacement plethysmography test in 224 healthy boys and girls (11.2 +/- 3.2 years, 45.3 +/- 18.7 kg, 149.9 +/- 18.5 cm). Study 2 cross-validated the prediction equations in a separate cohort of 62 healthy boys and girls (11.2 +/- 3.4 years, 44.2 +/- 15.3 kg, 149.4 +/- 19.3 cm).
  
  
  RESULTS
  In Study 1 (development of TGV prediction equations), the quadratic relationship using height as the independent variable and the measured TGV as the dependent variable yielded the highest adjusted R(2) and the lowest SE of estimate in both genders, thus producing the following prediction equations: TGV = 0.00056 x H(2) - 0.12422 x H + 8.15194 (boys) and TGV = 0.00044 x H(2) - 0.09220 x H + 6.00305 (girls). In Study 2 (cross-validation), no significant difference between the predicted and measured TGVs (-0.018 +/- 0.377 liters) was observed. The regression between the measured TGV and the predicted TGV yielded a slope and intercept that did not significantly differ from the line of identity. Prediction accuracy was good as indicated by a high R(2) (0.862) and low SE of estimate (0.369 liters).
  
  
  CONCLUSIONS
  The new child-specific TGV prediction equations accurately, precisely, and without bias estimated the actual TGV of 6- to 17-year-old children.
authors.affiliation: Department of Health and Sport Sciences, University of Oklahoma, Norman, OK 73019, USA. dafields@ou.edu
authors.forename: David A
authors.initials: DA
authors.lastname: Fields
authors.forename: Holly R
authors.initials: HR
authors.lastname: Hull
authors.forename: A J
authors.initials: AJ
authors.lastname: Cheline
authors.forename: Manjiang
authors.initials: M
authors.lastname: Yao
authors.forename: Paul B
authors.initials: PB
authors.lastname: Higgins
mesh_terms: D000293:Adolescent; D000886:Anthropometry; D001823:Body Composition; D001827:Body Height; D015992:Body Mass Index; D001835:Body Weight; D002648:Child; D005260:Female; D006801:Humans; D008297:Male; D010991:Plethysmography / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013909:Thorax / Q000033:anatomy & histology; D013990:Tidal Volume