 One certified anesthesiologist, proficient in lung ultrasound, will perform all sonographic evaluations using a MyLab Five Esaote, Italy ultrasound device. A linear ultrasound transducer will be placed perpendicular to two consecutive ribs on the parasternal line of each hemithorax and the lung sliding will be evaluated using both B-mode and M-mode in each abovementioned phase lasting 10 seconds. B-mode evaluations will be registered as clips while M-mode ones will be registered as pictures. 