Resistivity coefficients for body composition analysis using bioimpedance spectroscopy: effects of body dominance and mixture theory algorithm

Abstract

Body composition is commonly predicted from bioelectrical impedance spectroscopy using mixture theory algorithms. Mixture theory algorithms require the input of values for the resistivities of intra-and extracellular water of body tissues. Various derivations of these algorithms have been published, individually requiring resistivity values specific for each algorithm. This study determined apparent resistivity values in 85 healthy males and 66 healthy females for each of the four published mixture theory algorithms. The resistivity coefficients determined here are compared to published values and the inter-individual (biological) variation discussed with particular reference to consequential error in prediction of body fluid volumes. In addition, the relationships between the four algorithmic approaches are derived and methods for the inter-conversion of coefficients between algorithms presented.

Classification of Hydration in Clinical Conditions: Indirect and Direct Approaches Using Bioimpedance

“…Uncertain basic assumptions and constants of the original BIS approach [26,27,28,29] resulted in errors in the predictions of fluid volumes. Specifically, significant errors in the estimation of TBW (2 L) and ECW (~1 L) in individuals with increasing adiposity, characterized using BMI, were explained as the effect of increasing adipose tissue on the assumed resistivity of the ECW [30,31,32].…”

An objective measure for the assessment and management of fluid shifts in acute major burns

“…Although ECF was not associated with time, the p value (0.15) is arguably low enough to accept that a clinical relationship may exist despite a small sample. In contrast, the embedded algorithm of analysis may explain why ECF is not associated with time in this population (each algorithm has different constants for estimating the individual fluid compartments [ 43 ]). However, R 0 , the equivalent resistance of ECF significantly changed with time, suggesting fluid volume change in the extracellular compartment is associated with time.…”

Bedside quantification of fat-free mass in acute spinal cord injury using bioelectrical impedance analysis: a psychometric study

“…This method requires the use of apparent resistivity coefficients for ECW and ICW. These have not been determined for SCI patients; consequently values were taken from the largest data set published to date [21].…”

“…FFM was predicted from BIS data (BIS LCW ) [21]. BIS uses fundamental prediction methods (mixture theory) rather than specific empirical prediction equations, with assumed coefficients for body density, body proportion and fluid resistivities [22].…”