Fig. 1

Ultrasound assessment of lung aeration score (LUS). Images a and b show 6 lung regions of the right lung; antero-superior (1), antero-inferior (2), latero-superior (3), latero-inferior (4), postero-superior (5), and posterior-inferior (6). Lung areas are delineated by parasternal (PSL), anterior axillary (AAL), posterior axillary (PAL), and paravertebral (PVL) lines. A numeric value was assigned to each lung area according to the most severe lung ultrasound finding. Images c, d, e, and f show typical images corresponding respectively to the degree of lung aeration loss. Image c shows normal lung image with presence of horizontal A lines (numeric value = 0); Image d shows the presence of multiple well-defined and spaced B1 lines issued from a small juxtapleural consolidation (numeric value = 1); image e shows multiple coalescent vertical B2 lines issued from the pleural line (numeric value = 2); image f shows the presence of tissue pattern containing either hyperechoic punctiform or linear images (numeric value = 3). LUS is calculated as the sum of the numeric values assigned to 12 lung zones ranging from 0 and 36