Introduction: Unanticipated difficult laryngoscopic tracheal intubation accounts for a significant proportion of adverse anaesthetic outcome in clinical practice. Hence, it is important to identify patients with difficult airway preoperatively. In our study, we have compared the upper lip bite test with modified Mallampati classification in predicting difficulty in endotracheal intubation.

Materials and Methods: The study was conducted on 150 ASA I patients of either sex, aged more than 18 years scheduled to undergo elective surgery under general anaesthesia and endotracheal intubation. Pre-operatively airways of the patients were evaluated using modified Mallampati test and upper lip bite test. MMT class III and class IV and ULBT class III were considered potentially difficult intubation. Experienced anaesthesiologists unaware of pre-operative airway evaluation, will perform laryngoscopy and grade the glottic view as per Cormack and Lehane’s classification. Grade III and IV were considered as difficult intubation. Sensitivity, specificity, accuracy, positive and negative predictive values of ULBT and MMT were calculated.

Results: MMT was more sensitive (71.43%) than ULBT (28.57%). MMT had a specificity of 81.82 as compared to 96.5% for ULBT. Positive predictive value for MMT is 16.3% and 28.57% for ULBT. Negative predictive value was 98.32% and
96.50% for MMT and ULBT respectively. Accuracy of MMT was 81.33% while it was 93.33% for ULBT.

Conclusions: Modified Mallampati test is an inherently better test at predicting difficult endotracheal intubation when compared to upper lip bite test. Both modified Mallampati and upper lip bite test are better predictors of easy intubation rather than as positive predictors of difficult intubation.