EVALUATION OF MULTIPLE FREQUENCY BIOELECTRICAL-IMPEDANCE AND COLE-COLE ANALYSIS FOR THE ASSESSMENT OF BODY-WATER VOLUMES IN HEALTHY HUMANS

Objective: To assess the application of a Cole-Cole analysis of multip le frequency bioelectrical impedance analysis (MFBIA) measurements to predict total body water (TEW) and extracellular water (ECW) in humans . This technique has previously been shown to produce accurate and rel iable estimates in both normal and abnormal animals. Design: The whole body impedance of 60 healthy humans was measured at 496 frequencies ( ranging from 4 kHz to 1 MHz) and the impedance at zero frequency, R(0) , and at the characteristic frequency, Z(c), were determined from the impedance spectrum, (Cole-Cole plot). TEW and ECW were independently d etermined using deuterium and bromide tracer dilution techniques. Sett ing: At the Dunn Clinical Nutrition Centre and The Department of Bioch emistry, University of Queensland. Subjects: 60 healthy adult voluntee rs (27 men and 33 women, aged 18-45 years).Results: The results presen ted suggest that the swept frequency bioimpedance technique estimates total body water, (SEE = 5.2%), and extracellular water, (SEE = 10%), only slightly better in normal, healthy subjects than a method based o n single frequency bioimpedance or anthropometric estimates based on w eight, height and gender. Conclusions: This study has undertaken the m ost extensive analysis to date of relationships between TEW (and ECW) and individual impedances obtained at different frequencies ( > 400 fr equencies), and has shown marginal advantages of using one frequency o ver another, even if values predicted from theoretical bioimpedance mo dels are used in the estimations. However in situations where there ar e disturbances of fluid distribution, values predicted from the Cole-C ole analysis of swept frequency bioimpedance measurements could prove to be more useful.