Clinical Study to Compare Bedside Tests - Mallampati Score, Upper Lip Bite Test, and Thyromental Distance - With...

Anticipation of a difficult airway is essential for safe anesthesia. Unanticipated difficult intubations remain a major cause of morbidity and mortality in the perioperative period. Several bedside airway assessment tests exist, but their accuracy varies.

To compare the predictive value of the Modified Mallampati Test (MMT), Upper Lip Bite Test (ULBT), and Thyromental Distance (TMD) against the Cormack-Lehane (CL) grading for predicting difficult intubation.

A prospective observational study was conducted on 150 ASA I-II patients (18-60 years) scheduled for elective surgery under general anesthesia. Preoperative airway assessment included MMT, ULBT, and TMD performed by a single anesthesiologist. Direct laryngoscopy was performed under standardized anesthesia, and CL grades were recorded. Grades III-IV were considered difficult intubation. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of each bedside test were calculated using CL grading as the gold standard.

Difficult intubation was encountered in 20 patients (13.33%), with 18 graded CL III and 2 graded CL IV. Sensitivity and specificity were: MMT - 45% and 96.15%; TMD - 65% and 94.61%; ULBT - 80% and 96.92%. ULBT showed the highest predictive accuracy.

ULBT demonstrated superior sensitivity and specificity among the tests evaluated, but no single bedside test was sufficiently accurate to predict all difficult intubations. A combination of tests is recommended for preoperative airway assessment.