The Correlations of the Findings Obtained From Airway Ultrasonography With Cormack Lehane Classification in Patients With Obstructive Sleep Apnoea - A Cross Sectional Study

Research design

1. This is a cross sectional study. Involving face-to-face interview, USG airway assessment and Cormack Lehane score assessment. The patient will be identified from locations listed below:

• Anaesthesia clinic
• In the ward, during review by anaesthesia team for elective operation in the following day
• In the ward, when cases are notified for operations as emergency case

2. Once consent obtained from the patient, information regarding surgery and date of surgery will be recorded in the patient's data collection sheet. Patient's STOPBANG score and AHI score will also be recorded.
3. The airway ultrasonography will be performed by the principal investigator using a standardized ultrasound machine (NextGen LOGIC e Ultrasound with 12L-RS wide band linear array 5-13 MHz frequency probe) under supervision by a radiologist. The procedure will be performed at the recovery bay in the operation theatre. The following measurements will be done and recorded for future statistical analysis.

• Depth of preepiglottic space (PE)
• Distances between epiglottis and midpoint between 2 vocal cords (E-VC)

4. Cormack Lehane score will be obtained during induction of General Anaesthesia and Intubation in OT on the specified OT date. Conventional direct laryngoscope will be used for CL score determination. Medical Officer of more than 2 years' experiences in anaesthesiology will be requested to intubate the patient to minimize bias. CL scores are as described below

CL 1: Most of glottis Visible CL 2: Half of the glottis seen CL 3: Only epiglottis visible CL4: No laryngeal structure visible