“Unlocking Airway Predictability: The Role of Ultrasound in Assessing Cormack-Lehane Grade Through Anterior Neck Soft Tissue Thickness at the Level of Vocal Cords and Hyoid Bone”

Abstract

Introduction: Endotracheal intubation in the emergency department can be challenging due to difficult airways. The Cormack-Lehane score helps assess intubation difficulty based on laryngoscopic views, with higher scores indicating poorer visibility. This study examines whether point-of-care ultrasound measurements of anterior neck soft tissue thickness at the vocal cords and hyoid bone can predict difficult intubations with Macintosh blade. Methodology: Prospective observational study included 100 patients over 18 years old who required rapid sequence intubation in emergency department at a tertiary care hospital in India, from March to December 2023. Patients with cervical spine pathology and pregnant women were excluded. Ultrasound measurements of anterior neck soft tissue thickness were taken at the vocal cords and hyoid bone. Direct laryngoscopy with a Macintosh blade was then performed, and the CL grade was recorded. Intubation difficulty was categorized based on CL grades 1-2 (easy) and 3-4 (difficult). Diagnostic performance metrics, including sensitivity, specificity, and Area under the Receiver Operating Characteristic Curve (AUROC), were calculated. Results: The study found that increased anterior neck soft tissue thickness at both the hyoid bone and vocal cords was significantly associated with higher CL grades (P < .001). The AUROC values were 0.961 for hyoid bone measurements and 0.970 for vocal cords measurements, indicating high diagnostic accuracy. The sensitivity and specificity of these measurements suggest they are effective predictors of difficult intubation. Notably, higher ANS measurements correlated with a higher likelihood of requiring multiple intubation attempts. Conclusion: This study supports the use of ultrasound-measured anterior neck soft tissue thickness at the hyoid bone and vocal cords as effective predictors of difficult intubation. The high accuracy and statistical significance of these measurements suggest they can improve pre-intubation assessments and guide clinical decisions. Using these ultrasound measurements in routine practice could help better predict intubation challenges and improve patient outcome.