title: Evaluation of a new pediatric air-displacement plethysmograph for body-composition assessment by means of chemical analysis of bovine tissue phantoms.
abstract: BACKGROUND
  Body-composition assessment reflects infant growth and nutritional status but is limited by practical considerations, accuracy, and safety.
  
  
  OBJECTIVE
  This study evaluated the precision and accuracy of a new air-displacement plethysmography (ADP) system for pediatric body-composition assessment.
  
  
  METHODS
  We used 24 phantoms constructed from bovine lean muscle and fat. The phantoms varied in mass (1.3894-9.9516 kg) and percentage fat (%Fat; 2.08-34.40%), thereby representing infants between birth and 6 mo of age. Estimates of %Fat obtained with chemical analysis (CA), hydrostatic weighing, and ADP were compared.
  
  
  RESULTS
  There was no significant difference between %Fat measured with ADP (%Fat(ADP)) and %Fat measured with CA (%Fat(CA)); the mean values were 18.55% and 18.59%, respectively. SDs for %Fat(ADP) and %Fat(CA) were not significantly different (0.70% and 0.73%, respectively). %Fat measurements obtained with ADP, CA, and hydrostatic weighing were highly correlated (r > 0.99, P < 0.0001). The regression equation (%Fat(CA) = 0.996%Fat(ADP) + 0.119; SEE = 0.600; adjusted R(2) = 0.997; P < 0.0001) did not differ significantly from the line of identity (%Fat(CA) = %Fat(ADP)). There was high agreement between individual measurements of %Fat(ADP) and %Fat(CA), as shown by the narrow 95% limits of agreements between methods (-1.22% to 1.13%), and there was no systematic bias in individual differences across the phantom mass and %Fat ranges.
  
  
  CONCLUSIONS
  ADP provides a highly precise and accurate estimate of %Fat in bovine tissue phantoms in the pediatric ranges of body weight and body fatness.
authors.affiliation: Department of Animal Science, the University of California, Davis, 95616-8521, USA. rdsainz@ucdavis.edu
authors.forename: Roberto D
authors.initials: RD
authors.lastname: Sainz
authors.forename: Alessandro
authors.initials: A
authors.lastname: Urlando
mesh_terms: D000273:Adipose Tissue / Q000033:anatomy & histology; D000388:Air; D000818:Animals; D001823:Body Composition; D001835:Body Weight; D002417:Cattle; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D023421:Models, Animal; D018482:Muscle, Skeletal / Q000033:anatomy & histology; D019047:Phantoms, Imaging; D010991:Plethysmography / Q000379:methods*; D015203:Reproducibility of Results; D012449:Safety; D012680:Sensitivity and Specificity