Comparative Study of Preoperative Airway Assessment by Conventional Clinical Predictors and Ultrasound-Assisted Predictors.

Aims: The aim of this study is to evaluate the effectiveness of airway sonographic parameters as the predictors of difficult laryngoscopy and to evaluate the validity of combined sonographic and clinical tests.

Materials And Methods: This prospective and observational study analyzed a sample of 200 patients who were categorized as having easy (Grades 1 and 2) or difficult (Grades 3 and 4) laryngoscopy based on the laryngoscopic criteria of Cormack-Lahane (CL). Sonographic parameters, including the anterior neck soft-tissue thickness at the level of vocal cord (ANS-VC), ANS tissue thickness at the level of hyoid, and ratio of depth of pre-epiglottic space to distance from epiglottis to midpoint of the distance between vocal cords and clinical parameters, including modified Mallampati class, thyromental distance, and hyomental distance ratio (HMDR), were analyzed. Univariate and multivariate regression analysis was used for the statistical analysis.

Results: Twenty patients (10%) were categorized as having difficult laryngoscopy. Statistically significant differences between patients with difficult and easy laryngoscopy were noted for 5 of 6 parameters. The diagnostic validity profiles showed variable sensitivity (26.5%-87.5%) and good specificity (58.9%-94.2%) and negative predictive value (88.8%-97.03%). ANS-VC has the highest sensitivity (87.50%) and area under curve value (0.887), whereas HMDR showed highest specificity (94.2%) and highest accuracy (89.60%) which means it has low false-positive prediction rate. The combination of tests improved the diagnostic validity profile (highest area under the curve, 0.897).

Conclusion: Sonographic predictors can help in identifying difficult laryngoscopy. Combined clinical and ultrasonographic parameters showed better validity profiles in comparison to the individual tests.