Figure 2
Upper left: Bland–Altman plot depicting the cohort-wise agreement between the EIT-derived SPAP (SPAPEIT) and the TTE-derived SPAP (SPAPTTE). Each type of symbol represents an oxygen saturation level (SpO2), showing n = 70 paired values in normoxemia (filled circle, SpO2 ≥ 95%), n = 48 paired values in mild hypoxemia (filled square, 90% > SpO2 ≥ 80%), and n = 48 paired values in profound hypoxemia (filled triangle, 80% > SpO2 ≥ 65%), for a total of n = 166 paired values. In terms of accuracy, an average difference (bias) of − 0.1 mmHg was found between both methods and is depicted as a solid line. In terms of precision, the standard deviation (SD) of the paired differences was found to be 4.5 mmHg, resulting in 95% limits of agreement (bias ± 1.96 SD) of [− 8.9, 8.7] mmHg, depicted as dashed lines. Upper right: Correlation plot between SPAPEIT and SPAPTTE, with a cohort-wise Pearson’s correlation coefficient of 0.76 (P \(\ll\) 0.001). Bottom: Bland–Altman plots for each SpO2 level separately. EIT electrical impedance tomography, TTE transthoracic echocardiography, SPAP systolic pulmonary artery pressure.
