Obstructive sleep apnoea (OSA) is the most serious kind of the sleep-disordered breathing group, characterised by recurrent episodes of partial to complete obstruction of the upper airway resulting in inefficient alveolar gas exchange and desaturation[1].

It is a commonly encountered condition with a reported prevalence of 9-25% in the general population [2].

However, the majority of OSA patients presenting for surgery remain undiagnosed or untreated[3], contributing to a high rate of unexpected adverse airway outcome[4].

The various airway abnormalities represented by OSA include a large tongue, collapsible airway and crowding of the oropharyngeal structures, among others[5].

Accurate airway assessment should always be performed so as to provide appropriate planning and management of expected difficult intubation, but the common clinical screening tests (Mallampati score, inter-incisor distance, mento-hyoid distance, BMI, etc ) have shown low sensitivity and specificity with a limited predictive value, especially if only a single assessment method is used[6].

Ultrasonography could be a highly sensitive and specific tool for prediction of difficult intubation in OSA patients presented for elective surgery by measuring tongue base thickness, distance between lingual arteries, hyo-mental distance and condylar mobility.

Inclusion Criteria:

1. 21-60 years old
2. ASA I, II, or III
3. STOP-BANG scoring >3

Exclusion Criteria:

• 1) Age <21 years old 2) patients with cervical spine injury, limited neck mobility, neck swelling 3) patients with lost incisor teeth 4) asymmetric mobility of the temporomandibular joint as in maxillofacial injuries/malignancies prior to surgery on the airway 5) pregnancy

This study will be carried out on OSA patients prepared for elective surgery under general anaesthesia with tracheal intubation from Tanta University Hospitals