Body fluid volume determination via body composition spectroscopy in health and disease

Abstract

The assessment of extra-, intracellular and total body water (ECW, ICW, TBW) is important in many clinical situations. Bioimpedance spectroscopy (BIS) has advantages over dilution methods in terms of usability and reproducibility, but a careful analysis reveals systematic deviations in extremes of body composition and morbid states. Recent publications stress the need to set up and validate BIS equations in a wide variety of healthy subjects and patients with fluid imbalance. This paper presents two new equations for determination of ECW and ICW (referred to as body composition spectroscopy, BCS) based on Hanai mixture theory but corrected for body mass index (BMI). The equations were set up by means of cross validation using data of 152 subjects (120 healthy subjects, 32 dialysis patients) from three different centers. Validation was performed against bromide/deuterium dilution (NaBr, D2O) for ECW/TBW and total body potassium (TBK) for ICW. Agreement between BCS and the references (all subjects) was -0.4 +/- 1.4 L (mean +/- SD) for ECW, 0.2 +/- 2.0 L for ICW and -0.2 +/- 2.3 L for TBW. The ECW agreement between three independent reference methods (NaBr versus D2O-TBK) was -0.1 +/- 1.8 L for 74 subjects from two centers. Comparing the new BCS equations with the standard Hanai approach revealed an improvement in SEE for ICW and TBW by 0.6 L (24%) for all subjects, and by 1.2 L (48%) for 24 subjects with extreme BMIs (<20 and >30). BCS may be an appropriate method for body fluid volume determination over a wide range of body compositions in different states of health and disease.

Bioelectric impedance spectroscopy underestimates fat-free mass compared to dual energy X-ray absorptiometry in incurable cancer patients

“…FFM BIS , estimated by original equations for Xitron Hydra (Xitron, 1997;Matthie, 2005). FFM BCS , estimated by equations from BCS (Moissl et al, 2006). FFM TBWBIS , estimated from TBW by BIS divided by 0.73 (Ellis, 2000 …”

“…Furthermore, we tested the ability of a new set of equations based on measurements by Xitron Hydra in both healthy subjects and renal patients, validated by isotope dilution (tritium and bromide) and by whole-body counting (total body potassium, TBK) (Moissl et al, 2006). With this approach, termed body composition spectroscopy (BCS) the parameters r ECW , r ICW , K B and density (D) are combined into two parameters k ECW and k ICW to yield two BCS equations for ECW BCS and ICW BCS :…”

“…The parameters were determined as a ¼ 0.188, b ¼ 0.2883, c ¼ 5.8758 and d ¼ 0.4194 by cross-validation (Moissl et al, 2006). ECW BCS and ICW BCS were converted to FFM BCS by Equation (4).…”

An analog front-end enables electrical impedance spectroscopy system on-chip for biomedical applications

“…The continuous progress of medical applications of electrical bioimpedance spectroscopy (EBIS) (Aberg et al 2005, Moissl et al 2006, Caduff et al 2006, combined with recent advances in textile electrode technology (Pacelli et al 2006, Paradiso andDe Rossi 2006), enable the development of bioimpedance-based measurement systems for home monitoring (Medrano et al 2007 and personal monitoring (Scheffler et al 2003).…”

Wearable sensors: can they benefit patients with chronic kidney disease?

“…Measuring a whole spectrum allows differentiation between two compartments, being extracellular water and ICW, with fat mass and fat-free mass estimated using empirical equations. The combined efforts of Moissl et al and Chamney et al resulted in a further refined three-compartment model, which includes fluid overload as a separate measurable compartment, enabling discrimination between fluid overload and muscle mass [98,99]. BIA is operator independent and easy to use for nutritional and body composition assessment in ESRD patients [100].…”