On the day of surgery, all patients will receive an injection pantoprazole 40 mg and injection ondansetron 4 mg for aspiration prophylaxis in the preoperative room. After ensuring routine fasting ,all patients were monitored using electrocardiography, non-invasive blood pressure, pulse oximetry, and temperature monitoring on the day of the operation. Preoxygenation will be performed for 3 min while the patient will be kept in the ramp position. Standard anesthesia induction (propofol 2 mg.kg-1, fentanyl 2 mcg.kg-1, rocuronium bromide 0.6 mg.kg-1 intravenously) will be done. After 3 minutes of bag and mask ventilation (with or without adjunct such as oral or nasal airway), direct laryngoscopy and intubation will be performed using an appropriate size video laryngoscope. An Anesthesiologist with at least 3 years of experience will perform laryngoscopy and intubation.

Laryngoscopy and intubation difficulty level for both clinical assessment using (SARI) score and ultrasound assessment of airway will be validated against Intubation Difficulty Scale. The IDS score is the sum of these seven parameters viz: (1) Number of attempts, (2) Number of additional operators, (3) Alternative techniques, (4) Cormack-Lehane grade, (5) Lifting force, (6) External laryngeal pressure, (7)vocal cord mobility. The score interpretation 0: Easy intubation, 1-5: slightly difficult intubation,>5:moderate to major difficulty.