Prediction of Difficult Laryngoscopy Using the Mallampati Scale

Abstract

Introduction: Preoperative airway assessment is mainly performed using the Mallampati scale. Aim: Evaluation of the specificity, sensitivity, and positive and negative predictive values of the Mallampati scale, used for difficult laryngoscopy prediction in adult Greek patients. Method: A prospective study was conducted on 150 patients who underwent elective surgery under general anaesthesia during the last four months of 2012. Preoperative airway assessment was performed using the modified Mallampati scale I–IV. During direct laryngoscopy, the patients were classified using the Cormack and Lehane scale I–IV. For data collection, a formal questionnaire was used. Pearson’s x2 test was performed for comparisons between proportional data and Student’s t-test for qualitative data. The predictive value of III or IV on the Mallampati scale for prediction of difficult laryngoscopy (Cormack and Lehane III or IV) was determined by logistic regression analysis. A p value of ≤5% was considered significant, by using the Statistical Package for Social Sciences (SPSS), v. 17.0 and STATA, v. 8.0. Results: The Mallampati scale had a sensitivity of 64.2%, a specificity of 79.4%, a positive predictive value of 63.0% and a negative predictive value of 80.2%. The rate of correlation between the Mallampati and the Cormack and Lehane scales was 74.0%. When compared with Mallampati class I or II, Mallampati classification III or IV proved to be a significant predictive factor of difficult laryngoscopy (p<0.001). Conclusions: Despite the fact that the Mallampati scale has low sensitivity and specificity, Mallampati classification III or IV has significant predictive value for difficult laryngoscopy.