Comparison of Upper Lip Bite Test and Thyromental Distance with Other Airway (Malampatti and Inter Incisor Distance) Assessment Tests for Predicting Difficult Endotracheal Intubation

Objective: To study the ability of upper lip bite test and thyromental distance to predict difficult endotracheal intubation when compared to standard assessment tests such as Mallampati and inter incisor distance. Study Design: Cross-sectional validation study. Place and Duration of Study: Department of Anesthesiology, Pak-Emirates Military Hospital, Rawalpindi, Pakistan, Sep 2020 to Mar 2021. Methodology: We studied a total of 50 patients who reported for the administration of general anesthesia. All patients underwent evaluation with modified Mallampati test, upper lip bite test and thyromental distance test. All participants underwent subsequent intubation according to a standard protocol. The researcher documented difficult intubations. Results: We found the upper lip bite test to have a sensitivity of 75.7%, a specificity of 84.2%, and a diagnostic accuracy of 78.6%. Thyromental distance had a sensitivity, specificity, and diagnostic accuracy of 51.4%, 78.9% and 60.7%, respectively while the modified Mallampati had a sensitivity of 64.9%, 89.5%, specificity and a diagnostic accuracy of 73.2%. Conclusion: Upper lip bite test is a useful bedside assessment tool with which to predict the probability of a difficult endotracheal intubation. Height to thyromental distance ratio test is also acceptable for rapid assessment.