Differences in the Electrical Impedance Spectroscopy Variables Between Right and Left Forearms in Healthy People: A Non Invasive Method to Easy Monitoring Structural Changes in Human Limbs?

The resistive component of bioimpedance was non invasively assessed in both right and left upper arms of 11 healthy female and 9 male subjects (28.4 ± 1.4 years; 63.8 ± 11.8 kg; 167.4 ± 7.5 cm) all of whom were right-handed. A homemade electrical impedance spectroscopy device which implemented the AD 5933 electronic board was utilized, and the bipolar modality of bioimpedance assessment was chosen using two disposable ECG surface electrodes placed at each end of the biceps brachial muscles while subjects were sitting comfortably. Upper arm resistance was acquired at sweeping frequency steps of 15, 30, 45, 60 and 75 kHz. Results showed a significantly lower mean value of resistance in right versus left upper arms: −27.4 Ω, P < 0.05 or about −4%, at the frequency of 15 kHz. It was concluded that some errors of data interpretation may occur in the case of lymphedema in one arm and thus, electrical impedance spectroscopy was utilized to monitor the water volume trend in that arm in comparison with the other arm. These results underline a predominantly low value of the resistance in the main upper arm compared to that in the auxiliary one, even in healthy subjects. Therefore, care must be taken when the electrical impedance spectroscopy is adopted in these clinical assessments.