Grayscale lung ultrasound examination (transverse scan between intercostal fields; linear probe with 12 MHz frequency) shows a normal lung ultrasound pattern: hyperechoic, regular, and smooth pleural line with a thickness of less than 0.5 mm (arrows), pleural sliding present, and normally represented characterized by “to and fro” movement of lung surface synchronized with respiration (Electronic Supplementary Video 1). Below the pleural line, lung ultrasound imagines show A-lines (arrowheads): echogenic horizontal lines parallel and equidistant from each other which indicate the presence of normally aerated lung.