Study protocol and anesthesia practice Patient's demographic and history of snoring or asthma/hyper-reactive airway were obtained by research assistant at preinduction period. Standard monitoring including non-invasive blood pressure, pulse oximetry, electrocardiography and capnography were applied to all patients before starting general anesthesia. All patients were received general anesthesia with oroendotracheal tube intubation. Induction techniques were either inhalation anesthetic agent by N2O-O2-sevoflurane or intravenous agent with 100% O2. Type of anesthetic circuit used (Circle or Jackson-Rees) was depending on anesthesiologist in charge. Patients head position were in neutral under small head ring to prevent head movement during induction. Maneuvers on bag mask ventilation such as application of CPAP with opening airway maneuvers, oropharyngeal airway or two person ventilations were recorded by research assistant at induction period. When positive pressure ventilation was difficult after the patients had been slept, the CPAP ≥5 cmH2O was applied incorporated with opening airway by head tilt/chin lip or jaw thrust until assisted spontaneous ventilation was successful. Then the next maneuvers on bag mask ventilation described above would be followed if bag mask ventilation was still not possible. Neuromuscular blocking agents for intubation were used or not depending on the discretion of the attending anesthesiologist. If anesthesiologist in charge found the bag mask ventilation was difficult, non-depolarizing muscle relaxant may be held until bag mask ventilation was successful or succinylcholine was given to assist laryngoscopy procedure. The laryngoscopists were nurse anesthetists student, anesthesia residents, nurse anesthetist and anesthesiologist staff. Number of intubation attempts, Cormack-Lehane laryngoscopic view, intubation time in second and presence of desaturation (SpO2 < 95%) were recorded by research assistant at intubation period. There were many optioned used to aid successful intubation such as applying BURP maneuver, endotracheal tube with stylet used, change to smaller endotracheal tube size, change laryngoscope type or change to more experience laryngoscopists. Attending anesthesiologists take responsibility over nurse anesthetists student, anesthesia resident and nurse anesthetists for first or second failure of intubation attempts.