Ultrasound Assessment of the Airway for Prediction of Difficult Intubation

Abstract

Background: Prediction of difficult laryngoscopy remains challenging using conventional bedside airway tests alone. Airway ultrasonography provides objective anatomical measurements that may improve preoperative identification of difficult airways.

Methods:This prospective observational study included 80 adults undergoing elective surgery under general anaesthesia with endotracheal intubation. Conventional airway assessment and preoperative ultrasonography were performed. Ultrasonographic parameters included skin-to-epiglottis distance (DSE), skin-to-hyoid distance, anterior neck soft-tissue thickness, tongue thickness, hyomental distances, hyomental distance ratio (HMDR), and Pre-E/E-VC ratio. Cormack–Lehane Grades I–II were classified as easy and Grades III–IV as difficult laryngoscopy. Diagnostic performance was assessed using ROC analysis.

Results:Difficult laryngoscopy occurred in 15/80 (18.8%) patients. Compared with easy laryngoscopy, difficult cases had greater DSE (2.58±0.38 vs 2.05±0.32 cm; p<0.001), anterior neck soft-tissue thickness (1.58±0.29 vs 1.32±0.25 cm; p=0.001), and tongue thickness (5.67±0.65 vs 5.15±0.61 cm; p=0.004), with lower HMDR (1.17±0.07 vs 1.26±0.08; p<0.001). DSE >2.30 cm showed an AUC of 0.87, with 80.0% sensitivity and 83.1% specificity, while HMDR <1.20 showed an AUC of 0.84 with 80.0% sensitivity and specificity. DSE and HMDR remained independent predictors of difficult laryngoscopy.

Conclusion:Airway ultrasonography provides useful objective prediction of difficult laryngoscopy. DSE and HMDR may be valuable adjuncts to conventional preoperative airway assessment.