Comparison of two bioimpedance spectroscopy techniques in the assessment of body fluid volumes

The present study aimed to compare the estimates of body liquid volumes performed by two bioimpedance spectrometry techniques. One based on a step response technique (BIS-PEB) and second one based on multifrequency Xitron Hydra 4200 equipment (Xitron Technologies, San Diego, CA, USA). The convenience sample was initially composed of 422 students from a military parachuting course of the Brazilian Army. From such sample 42 male students were randomly selected to be evaluated during three weeks. The anthropometrical characteristics of the sample can be summarized as: 25.18 plusmn 4.10 years old; weight equals of 76.77 plusmn 7.84 kg; height equals to 174.96 plusmn 5.67 cm; body mass index (BMI) equal to 25.05 plusmn 2.11 kg m^-2. Bland-Altman graphics were used to compare the two methods in what concerns to estimate of extracellular fluid (ECF), intracellular fluid (ICF), and total body water (TBW). One can observe that the estimates of the two techniques present a good correlation, especially in the case of ECF (r = 0.975). The present study indicates that BIS-PEB technique associated with De Lorenzo equation can supply noninvasive estimates of body fluid volumes comparable to Xitron Hydra 4200 equipment.