Comparison of upper lip bite test with Mallampati test in the prediction of difficult intubation at a tertiary care hospital of Pakistan

Objective: To determine the accuracy of the Upper lip bite test and Mallampati test in predicting difficult endotracheal intubation. Methods: The cross-sectional study was conducted at the Aga Khan University Hospital, a tertiary care facility in Karachi, Pakistan. Between June 1, 2007 and May 31, 2008, 324 adult patients undergoing elective surgeries requiring general anaesthesia with endotracheal intubations were enrolled. Pre-operatively upper lip bite test and Mallampati test were performed for the assessment of airway by a specifically trained observer. Laryngoscopic view was rated by using Cormack and Lehane laryngoscopic grading once the patient was fully anaesthetised using standard anaesthesia technique. Completed data sheets were analysed using SPSS version 10. McNemar test and rank correlation coefficient were used to compare the upper lip bite test and the Mallampati test. Results: Of the 324 patients, 56 (17.3%) were classified as cases of difficult intubation. Upper lip bite test showed significantly higher accuracy, positive predictive value and negative predictive value than the Mallampati test. Comparison of specificity, however, did not reveal any significant difference between the two tests. Conclusion: Upper lip bite test is an acceptable alternative as a single test to predict difficult intubation in addition to other tests of airway assessment for the prediction of difficult intubation.