BACKGROUND There are many tests to predict difficult intubation viz., Patil's measurement of Thyromental Distance, the Mallampati Test and the Wilson Scoring System, but these tests have been shown to have high false positive rates which detract their usefulness. 1, 2 The aim of this study is to compare the sensitivity, specificity, positive predictive value and negative predictive value of Upper Lip Bite Test with Modified Mallampati Test and Thyromental Distance in predicting difficult

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... ion. MATERIALS AND METHODS Two hundred patients between 16 -65 years of age of either sex undergoing elective surgical procedures under general anaesthesia were enrolled in the study. Pre-operative evaluation of airway was done by Modified Mallampati Test, Upper Lip Bite Test and Thyromental Distance. Modified Mallampati Test grade III and IV, Upper Lip Bite Test class III & TMD < 6.5 cm were considered as predictors of difficult intubation. On the day of surgery, patients were pre-medicated with Inj. Glycopyrrolate 0.005 mg/kg IV, Inj. Midazolam 0.05 mg/kg IV, and Inj. Fentanyl 2 µg/kg IV. Patients were pre-oxygenated with 100% oxygen, induced with Inj. Thiopentone 5 mg/kg IV and intubation was facilitated by Inj. Suxamethonium 1-2 mg/kg IV. Laryngoscopy was done in sniffing position, glottic views were graded according to the Cormack and Lehane classification. Patients of Cormack-Lehane grade III/IV were considered as difficult to intubate. TMD was measured using tape in centimetre. RESULTS In the present study, the sensitivity, specificity, positive predictive value and negative predictive value of Modified Mallampati test were 60%, 97.89%, 60% and 97.89% respectively. The sensitivity, specificity, positive predictive value and negative predictive value of Upper Lip Bite Test were 30%, 97.4%, 37.5% and 96.35% respectively. Also, the sensitivity, specificity, positive predictive value and negative predictive value of Thyromental Distance were 10%, 97.4%, 16.67% and 95.36% respectively. CONCLUSION Modified Mallampati Test has high sensitivity, specificity, positive and negative predictive values compared to Upper Lip Bite Test and Thyromental Distance test. So, it can be used as a simple bedside screening test for difficult intubation along with other tests. Upper Lip Bite Test is more accurate than Thyromental Distance and probably second most important test in prediction of difficult airway.