Multifrequency bioelectrical impedance analysis and bioimpedance spectroscopy for monitoring fluid and body cell mass changes after gastric bypass surgery

SummaryBackground & aimsThere is a growing need for clinically applicable body composition assessment tools for extremely obese individuals. The objective of this research was to evaluate several bioimpedance techniques for monitoring changes in fluid, particularly intracellular water (reflecting body cell mass) after bariatric surgery.DesignFifteen extremely obese women (body mass index: 48.9 ± 7.0 kg/m2; age: 48 ± 9 years) were assessed before (baseline; T1), and approximately 6 weeks after gastric bypass surgery (T2) by several multifrequency bioelectrical impedance analysis approaches (MFBIA; QuadScan 4000), a bioimpedance spectroscopy device (BIS; Hydra 4200), and multiple dilution.ResultsBIS provided intracellular water estimates that were comparable to criterion, based on mean comparisons, at both time points (T1: criterion: 24.2 ± 3.1 L, BIS: 24.0 ± 3.7 L; T2: criterion: 20.6 ± 3.7 L, BIS: 19.7 ± 3.2 L). MFBIA (with Deurenberg equations) provided comparable measures to criterion only at T2 (criterion: 20.3 ± 3.7 L, MFBIA: 20.6 ± 2.7 L). Both MFBIA (with QuadScan proprietary equations) and BIS produced estimates of intracellular water change that were comparable to dilution. There was substantial variability in individual volume measures.ConclusionsAlthough MFBIA and BIS hold promise as convenient techniques for assessing fluid changes, individual variability in measurements makes them impractical for assessment of extremely obese patients in the clinical setting.