Comparison of Modified Mallampati Score and Ultrasonographic Airway Assessment in Predicting Ease of Glottic Visualization: A Prospective Diagnostic Accuracy Study at a Tertiary Care Hospital in Pakistan.

INTRODUCTION

The accuracy of preoperative airway assessment remains a challenging issue. The modified Mallampati (MP) scoring system has been commonly employed, though with poor predictive accuracy. The ultrasonographic measurement of skin-to-epiglottic distance (SED) has been proposed as an objective tool. We evaluated the accuracy of MP scoring and ultrasonographic measurement of SED in predicting easy glottic visualization based on Cormack-Lehane grading during direct laryngoscopy.

METHODS

This prospective observational diagnostic accuracy study involved 400 adult patients who underwent elective surgery under general anesthesia with an American Society of Anesthesiologists (ASA) grade of I and II. Preoperative MP score and SED by ultrasound examination were performed. The degree of glottic visualization was graded according to the Cormack-Lehane scale. Easy direct laryngoscopy was categorized as a Cormack-Lehane scale of I and II, while difficult direct laryngoscopy was categorized as a Cormack-Lehane scale of III and IV.

RESULTS

A significant association was observed between SED and Cormack-Lehane (CL) grade (p < 0.001). The mean SED increased progressively with worsening CL grade (p < 0.001). The area under the ROC curve (AUC) for SED was 0.98 compared with 0.50 for the MP score. At a cutoff >19.5 mm, SED demonstrated 100% sensitivity and 89.95% specificity. The MP score (>3.5) showed sensitivity of 6.25% and specificity of 99.46%. On multivariable analysis, SED was the only independent predictor of difficult laryngoscopy (OR 11.29, 95% CI 4.24-30.07; p < 0.001).

CONCLUSION

Ultrasonographic SED is a highly accurate and independent predictor of difficult glottic visualization and outperforms the modified Mallampati score. Incorporating airway ultrasound into routine preoperative assessments may improve the prediction of difficult glottic visualization.