Evaluation of a new pediatric air-displacement plethysmograph for body-composition assessment by means of chemical analysis of bovine tissue phantoms
2003
Sainz, R.D. | Urlando, A.
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. Design: 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 (%FatADP) and %Fat measured with CA (%FatCA); the mean values were 18.55% and 18.59%, respectively. SDs for %FatADP and %FatCA 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 (%FatCA = 0.996%FatADP + 0.119; SEE = 0.600; adjusted R2 = 0.997; P < 0.0001) did not differ significantly from the line of identity (%FatCA = %FatADP). There was high agreement between individual measurements of %FatADP and %FatCA, 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. Conclusion: ADP provides a highly precise and accurate estimate of %Fat in bovine tissue phantoms in the pediatric ranges of body weight and body fatness.
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