Inclusion Criteria:  All patients with American Society of Anaesthesiologist (ASA) physical status I-III Age (≥21-75 years old) General anaesthesia requiring tracheal intubation Provide written consent to participate in the study  Exclusion Criteria:  Pregnancy Body mass index (BMI) ≥ 35 Condition requires rapid sequence induction Need for fibreoptic intubation Need for nasal intubation Documented difficult airway during previous surgery Recent (3 months) active ischemic heart disease Recent (3 months) cerebrovascular disease Acute exacerbation of respiratory disease (eg. Uncontrolled asthma, Chronic Obstructive Pulmonary Disease)