Background: In the intensive care units, emergency, and operating rooms, ultrasound (US) has become a safe, simple, small, noninvasive, and portable technique for quick airway evaluation and management. This work aimed to assess the validity of ultrasound as regards the correlation to the Cormack-Lehane (CL) grading using direct laryngoscopy and for predicting the difficult airway.

Methods: A group of 140 patients, ASA I/II were selected in this prospective observational study who took part in elective surgical procedures that required intubation using direct laryngoscopy under general anesthesia. Prior to starting anaesthesia, an ultrasound image of the airway was recorded, and measurements were taken for the pre-epiglottic space (PES) depth and the distance between the epiglottis and vocal cords (E-VC). The CL grade was then matched to the ultrasound measures taken during direct laryngoscopy.

Results: There were positive significant correlations between difficult Laryngoscopy and ASA, number of attempts, PES, PES/E-Vc, time of US and complications (p<0.001). A negative significant correlation was revealed between difficult Laryngoscopy and E-Vc (p<0.001).

Conclusion: Patients with difficult airway could be better identified with sonographic assessment of the upper airway. The ratio of the pre-epiglottic space to the distance between the epiglottis and midway through the vocal cords proved a reliable predictor for the Cormack-Lehane grading compared to Mallampati grading in which increasing Pre E and the ratio of Pre E/E‑VC were associated with increased risk of difficult intubation