Bioimpedance spectroscopy technique: intra-, extracellular, and total body water

Abstract

The purpose of this study was to test the validity of a multiple frequency bioimpedance spectroscopy (BIS) technique that estimates extracellular fluid volume (ECV), intracellular fluid volume (ICV), and total body water (TBW). Thirteen healthy males (mean +/- SD: age, 23 +/- 3 yr; body mass, 80.6 +/- 14.7 kg) had their TBW and ECV measured by ingesting dilution tracers (7.27 g deuterium oxide, 1.70 g sodium bromide; blood samples at 0 and 4 h). ICV was calculated as TBW minus ECV. Impedance was measured (50-500 kHz) at rest, on a nonconducting surface, with a BIS analyzer. Electrode placement, posture, exercise, food/fluid intake, and ambient temperature were controlled. Dilution measures (TBW, 51.00 +/- 9.30; ECV, 19.88 +/- 3.14; ICV, 31.12 +/- 6.80 L) and BIS volumes (TBW, 50.03 +/- 7.67; ECV, 20.95 +/- 3.33; ICV, 29.04 +/- 4.51 L) were significantly different for ECV (P < 0.01) and ICV (P < 0.05); some individual differences were large. The correlation coefficients of dilution versus BIS volumes (r = 0.93 to 0.96) were significant at P < 0.0001; SEEs were: TBW, 2.23 L; ECV, 1.26 L; and ICV, 1.71 L. We concluded that BIS is valid for between-subject comparisons of body fluid compartments, is appropriate in clinical settings where change in ECV/ICV ratio is important, and should be used by comparing the required level of accuracy to the inherent technique error/variance.

A Replication Strategy for Distributed Real-Time Object-Oriented Databases

“…16 participants' ZOE2 values increased from pre-to post-practice and 13 decreased, while 14 participants' ZOEW values increased from pre-to post-practice and 15 decreased ( Figure 11). Similar to several previous investigations, our findings indicate that bio-electrical impedance as used in this study is not a valid measure of post-exercise mild dehydration in a field environment (Armstrong et al 1997;O'Brien et al 1999;Koulmann et al 2000;O'Brien et al 2002;Carter et al 2004;Casa et al 2005;Cheuvront 2005). …”

“…electrode placement, side of body, posture, limb position, ambient temperature, skin temperature, hydration status, food and liquid intake, fluid shifts, sweating, and recency of exercise (Caton et al 1988;Roos et al 1992;Shirreffs and Maughan 1994;Gudivaka et al 1996;Armstrong et al 1997;Cheuvront 2005). In this current study, ambient temperature could not have been an error source because it did not change from pre-to post-practice measurements.…”

“…Fluid and electrolyte shifts occur during and immediately following exercise which effect post-exercise bio-electrical impedance measurements (Koulmann et al 2000). Additionally, many of the sources of error associated with bio-electrical impedance measurement that can be controlled in a clinical or laboratory setting may not be controllable in a field setting such as: posture, limb position, ambient temperature, hydration status, food and liquid intake, fluid shifts, sweating, and recency of exercise (Caton et al 1988;Roos et al 1992;Shirreffs and Maughan 1994;Gudivaka et al 1996;Armstrong et al 1997;Cheuvront 2005).…”

Assessment of residual-limb volume change using bioimpedence

“…Bioimpedance analysis models for calculation of extracellular resistance and prediction of whole body extracellular water volume have been validated using deuterium oxide [5,[26][27][28] and bromide dilution techniques. With bromide dilution, considered the gold standard for V ECF assessment, whole body V ECF is determined from bromide concentrations in blood plasma following solution ingestion [19,28].…”

The Effect of Fluid Consumption and Exercise on Segmental Bioelectrical Impedance

“…Differences in volume and electrolyte content affect conductance and resistance of the applied current (resistance is the inverse to conductivity). The bioelectrical impedance method utilizes the greater conductivity of fat free mass and the greater resistance of the fat mass in the determination of body composition [15,16].…”