The study was performed by expert anesthesiologist in FOB intubation. In the preparation room, all patients was cannulated with a 20 gauge venous cannula and 0.02mg/kg Midazolam was given. Patient transferred to the operating room and was monitored with non-invasive blood pressure, pulse oximetry and ECG. After preoxygenation using a facemask for 5 min, induction of anesthesia was done with 2mg/kg propofol, 1 μg/kg of fentanyl and 0.6 mg/kg of atracurium.