Algorithm variations considered. For each tested algorithm (horizontal row), the indicated variations from baseline () are made.

<p>Algorithm variations considered. For each tested algorithm (horizontal row), the indicated variations from baseline () are made.</p

Area under the receiver operating characteristics curve (AUC), 95% confidence interval for AUC and p-value for different threshold criteria using the lung area estimation method (LAEM) and the coefficient of variation (CV).

<p>Comparison between patients suffering from acute respiratory distress syndrome (ARDS) and control patients without pulmonary pathologies.</p

Expected effects of changes in ventilation therapy.

<p>Peep, positive end-expiratory pressure; F_Io₂, fraction of O₂ in inspired gas.</p

Discrimination between ARDS and control using the lung area estimation method.

<p>(A) Receiver operating characteristics (ROC) curve for discrimination between ARDS and control subjects using the global inhomogeneity index and the lung area estimation method with a criterion of 50% of the maximum impedance change. (B) ROC curve for the same comparison using the coefficient of variation.</p

Creating an x-symmetrical region of interest (ROI) using the lung area estimation method (LAEM) in a patient with acute respiratory distress syndrome.

<p>From the raw image (A) a conventional functional ROI is created, in this example using a threshold criterion of 50% of the maximum impedance difference (B). In the next step (C), the ROI is mirrored by means of a Boolean “OR”-operation. The cardiac area is identified in the frequency domain (D, E) and subsequently subtracted from the x-symmetrical ROI to obtain the final LAEM ROI (F).</p

Finite element models used.

<p>Electrode nodes are indicated in green. <u>A</u>: 2D circular uniform FEM () <u>B</u>: 3D cylindrical uniform FEM () <u>C</u>: 3D cylindrical FEM with lung regions () <u>D</u>: 2D circular uniform FEM with electrode movement () (with arrows showing representative electrode movement).</p

EIT images for all algorithms from three representative animals.

<p>For each animal, images of V_T at ZEEP and Peep are shown individually normalized to the maximum amplitude in each image (<u>Blue</u>: decrease in conductivity, <u>Red</u>: increase in conductivity). Each column shows images for a different algorithm. Peep, positive end-expiratory pressure; ZEEP, zero end-expiratory pressure; V_T tidal volume.</p

Overview of the proposed methodology.

<p>Peep – positive end-expiratory pressure; F_Io₂ - fraction of oxygen in inspired gas; V – air volume; t – time; V_T – tidal volume; CoV - centre of ventilation; FEM – finite element model.</p

Sample image and identified end-inspiratory (blue) and end-expiratory (red) events.

<p><u>Left</u>: Image of average tidal volume change <u>Right</u>: Average EIT signal (arbitrary units) vs time (s) showing identified events.</p

Threshold criterion for functional regions of interest.

<p>Effect of threshold criterion using the functional region of interest (fROI) method on the global inhomogeneity (GI) index (A) and on the coefficient of variation (CV) (B) in ARDS and control patients. * p < 0.05 for comparison between ARDS and control patients.</p