Tidal volume monitoring by a set of tetrapolar impedance measurements selected from the 16-electrodes arrangement used in electrical impedance tomography (EIT) technique. Calibration equations in a group of healthy males

The mean R2 of the 20 equations determined by the 16-electrodes information, and for the best two 4-electrode configurations were 0.943 ± 0.010, 0.848 ± 0.062 and 0.690 ± 0.122, respectively. The error (%) of volume determinations obtained by the use of 16-electrodes, and by the use of the two best 4-electrode configuration with regarding to the real volume obtained by pneumotachometer were of 15 ± 6%, 16 ± 4% and 43 ± 41%, respectively. The volume differences between the one obtained by the use of 16-electrodes and that for the best 4 electrode configuration were not significant. We conclude that although the determinations of impedance obtained by the best 4-electrode configuration has a lower sensitivity than those obtained by the 16-electrodes, it is possible to measure the respiratory pattern in healthy males.