Comparing Efficacy of Modified Mallampati Test and Upper Lip Bite Test to Predict Difficult Intubation

Introduction: The failure to maintain a patent airway following induction of general anaesthesia can lead to disastrous complications. Hence, it is important to identify patients with difficult airway preoperatively. The present study was conducted to evaluate and compare efficacy of Modified Mallampati Test (MMT) and Upper Lip Bite Test (ULBT) to predict difficult intubation. Material and Methods: 200 patients undergoing elective surgeries under general anaesthesia with endotracheal intubation were enrolled in the study. Modified Mallampati Test (MMT) and Upper Lip Bite Test (ULBT) were performed on all patients preoperatively. MMT class III and class IV and ULBT class III were considered potentially difficult intubation. An experienced anesthesiologist, unaware of preoperative airway evaluation, performed the laryngoscopy and graded 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 (75.00%) than ULBT (25.00%); both tests had high specificity (MMT 91.30%; ULBT 95.11%). Positive predictive value was 42.86% for MMT while it was 30.77% for ULBT. Negative predictive value was 97.67% and 93.58% for MMT and ULBT respectively. Accuracy of MMT was 90.00% while it was 89.5% for ULBT. Conclusions: Both tests are good predictors of easy intubation but poor predictors of difficult intubation. MMT is better than ULBT at predicting difficult intubation.