Electrical impedance tomography: Intra and inter-rater reliability in healthy subjects

Background: Electrical impedance tomography (EIT) is an important noninvasive tool related for assessment of pulmonary ventilation.1 However, the intra and inter-rater reliability might not satisfactory because it is dependent on a specific positioning and the evaluator9s experience. Objectives: To assess the reliability of pulmonary ventilation measurements through EIT during spontaneous breathing in healthy subjects. Methods: Cross-sectional study with 19 healthy subjects assessed during quiet breathing, the Vital Capacity (VC) and Inspiratory Capacity (IC). The evaluations were performed through the EIT (Enligh, Timpel, Sao Paulo, Brazil) by intra and inter-rater. The variables were: tidal volume (Vt), VC, IC, and variations in total impedance during the Vt (ΔZVt), IC (ΔZIC) e VC (ΔZVC). Statistical analysis was performed by Intra Class Correlation (ICC), considered significant p Results: The inter-rater reliability values (ICC/ CI95%/ p-value) were: Vt (.672/.093to.884/.008), VC (.917/.557to.976/.000), IC (.917/.716to.964/.000), ΔZVt (.754/.376to.904/.002), ΔZVC (.868/.759to.963/.000) e ΔZIC (.895/.728to.959/.000). The intra-rater reliability values were: Vt (.469/-.581to.822/.124), VC (.412/-.753to.802/.166), IC (.644/-.620to.880/.032), ΔZVt (.871/.616to.957/.000), ΔZVC (.775/.329to.924/.004) e ΔZIC (.665/.003to.888/.025). Conclusions: Our results indicate that EIT is a reliable instrument, classified as satisfactory to excellent in the intra- and inter-examiner evaluations.