Ultrasound Measurement of Skin-to-Epiglottis Distance for Prediction of Difficult Airway in Adult Patients

Incidence of difficult laryngoscopy (Cormack-Lehane grade ≥ 3)

The proportion of patients with difficult laryngoscopy defined as Cormack-Lehane grade 3 or 4 during direct laryngoscopy.

Time frame: During intubation procedure (intraoperative period)

Intubation Difficulty Score (IDS)

Assessment of intubation difficulty using the Intubation Difficulty Score based on number of attempts, operators, alternative techniques, glottic exposure, lifting force, external laryngeal pressure, and vocal cord position.

Time frame: During intubation procedure

Correlation between ultrasound measurements and Mallampati score

Correlation between tracheal diameter and skin to epiglottis distance measured by ultrasound and preoperative Mallampati classification.

Time frame: Preoperative assessment

Skin-to-Epiglottis Distance Measured by Ultrasound

Skin-to-epiglottis distance will be measured using ultrasound immediately before anesthesia induction. The distance is recorded in millimeters (mm) as a continuous variable. Larger values indicate a greater skin-to-epiglottis distance and may be associated with an increased likelihood of difficult laryngoscopy. This is not a scored scale; therefore, no predefined minimum or maximum score exists.Cormack-Lehane Grading System. Scores range from Grade I to Grade IV. Grade I indicates full visualization of the glottis (easier laryngoscopy), whereas Grade IV indicates that neither the glottis nor the epiglottis is visible (most difficult laryngoscopy). Higher grades indicate a worse airway view.

Time frame: Immediately before induction of anesthesia