Air-displacement plethysmography for determining body composition in neonates: validation using live piglets

Area of Science:

• Animal physiology
• Body composition analysis
• Biomedical engineering

Background:

• Air-displacement plethysmography (ADP) is a noninvasive technique for assessing body composition, including fat mass (%FM) and lean body mass.
• Previous studies validated ADP indirectly through comparisons with labeled water dilution in infants and chemical analysis in phantoms.
• This study aimed to directly assess the precision and accuracy of ADP for %FM measurements in live animals against biochemical analyses.

Purpose of the Study:

• To evaluate the precision and accuracy of air-displacement plethysmography (ADP) for determining body fat percentage (%FM) in live animals.
• To compare ADP %FM measurements with direct biochemical analysis of whole-body lipid content.
• To determine the suitability of ADP for body composition assessment in animal models relevant to human infant studies.

Main Methods:

• Three groups of 12 piglets each underwent four body composition assessments using ADP at 2, 7, and 21 days of age.
• Following ADP measurements, piglets were euthanized for direct biochemical analysis to determine whole-body lipid content.
• Statistical analyses included linear regression and Bland-Altman analysis to assess agreement between ADP and biochemical methods.

Main Results:

• Mean %FM values from biochemical analysis and ADP were 8.63 ± 4.08% and 8.01 ± 4.03%, respectively, indicating good agreement.
• Linear regression and Bland-Altman analyses confirmed good concordance between ADP and biochemical measures of %FM.
• The root mean square coefficient of variation (RMS-CV) for ADP was 17.9%, with precision improving at higher fat mass ranges.

Conclusions:

• Air-displacement plethysmography (ADP) provides reasonably precise and accurate measurements of fat mass in piglets.
• ADP demonstrates good agreement with direct biochemical analysis for body composition assessment in this animal model.
• The findings suggest ADP is a viable tool for assessing body composition in animal models, particularly those relevant to the body weight range of low-birth-weight infants, despite lower precision in low %FM ranges.