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Abstract

Airway management is a cornerstone of safe anesthesia practice, and failure to anticipate a difficult airway can result in life-threatening complications. The Modified Mallampati Score (MMS) and Thyromental Distance Test (TMDT) are among the most widely used preoperative predictors. However, when used individually, their predictive accuracy remains variable. Combining these tests may improve diagnostic performance and support safer airway management in surgical patients.
Objective: To evaluate and compare the sensitivity, specificity, and predictive values of MMS and TMDT individually and in combination for predicting difficult intubation in apparently normal patients undergoing elective surgery.
Methods: This comparative observational study enrolled 150 patients with ASA physical status I or II scheduled for elective procedures under general anesthesia. Preoperative airway assessment was performed using MMS and TMDT, with Cormack–Lehane (CL) grading during laryngoscopy serving as the gold standard. Demographic data, surgical specialty, intubator experience, and the use of special equipment were recorded. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated for each test and their combination.
Results: MMS showed a sensitivity of 42.3%, specificity of 92.0%, PPV of 52.3%, and NPV of 88.4%. TMDT had a sensitivity of 23.07%, specificity of 92.0%, PPV of 37.5%, and NPV of 85.1%. The combined use of MMS and TMDT improved specificity to 98.4%, PPV to 66.7%, and maintained a high NPV of 84.8%, though sensitivity decreased to 15.4%. Difficult intubations were more frequent in females (80.8%) and general surgery cases (100%), while the use of special equipment was significantly associated with difficulty (p = 0.000).
Conclusion: While neither MMS nor TMDT alone offers both high sensitivity and specificity, their combined use enhances diagnostic accuracy and should be considered a valuable component of routine preoperative airway assessment.