LUS and Consequences of High FiO2 in Children

All children will be studied in the supine position. LUS will be performed with the portable device MicroMax (Sonosite, Bothell, Washington, USA) using a linear probe of 6 to 12 MHz. All ultrasound scans will be performed by the same anesthetist, who has experience of more than 30 lung ultrasound scans in pediatric patients. Each hemithorax will be divided into six regions, using three longitudinal lines (parasternal, anterior and posterior axillary) and two axial lines (one above the diaphragm and the other 1 cm above the nipples)