All the intubations will be performed by a well-trained anesthetist. The intubation attempt failure will be defined when the intubation time exceed 120 seconds, esophageal intubation occurred or desaturation with arterial oxygen saturation dropped below 90%. Three attempts will only allow,then anesthesia will be carried out according to decision of the attending anesthetist with exclusion of the case from the study. Face-mask intermittent positive pressure ventilation will be carried out in-between the attempts.