Lung Ultrasound Guided Choice of Best Positive End-Expiratory Pressure in Neonatal Anesthesia

The goal of this RCT is to demonstrate that, in neonatal anesthesia, the use of Lung Ultrasound (LUS) to guide choice of best Positive End-Expiratory Pressure (Peep) - the one that efficiently avoids lung atelectasis - leads to better gas exchange in the lung thus can lead to reduction of FiO2 applied to ventilatory setting in order to achieve same peripheral saturations of oxygen (SpO2). Specific aims of the study are: 1. to determine if LUS-guided PEEP choice in neonatal anesthesia, compared to standard PEEP choice, can lead to reduction of FiO2 applied to the ventilatory setting in order to maintain same SpO2s. 2. to determine if patients treated with LUS-guided PEEP will develop less postoperative pulmonary complications in the first 24 hours. 3. to compare static respiratory system compliance between groups. 4. to determine if there is a significant difference in hemodynamic parameters and amount of fluids infused or need for vasopressors between the two groups.