Diagnostic accuracy of bedside tests for predicting difficult intubation in Indian population: An observational study

Unanticipated difficult intubation can be challenging to anesthesiologists, and various bedside tests have been tried to predict difficult intubation. The aim of this study was to determine the incidence of difficult intubation in the Indian population and also to determine the diagnostic accuracy of bedside tests in predicting difficult intubation. In this study, 200 patients belonging to age group 18-60 years of American Society of Anesthesiologists I and II, scheduled for surgery under general anesthesia requiring endotracheal intubation were enrolled. Patients with upper airway pathology, neck mass, and cervical spine injury were excluded from the study. An attending anesthesiologist conducted preoperative assessment and recorded parameters such as body mass index, modified Mallampati grading, inter-incisor distance, neck circumference, and thyromental distance (NC/TMD). After standard anesthetic induction, laryngoscopy was performed, and intubation difficulty assessed using intubation difficulty scale on the basis of seven variables. The Chi-square test or student t-test was performed when appropriate. The binary multivariate logistic regression (forward-Wald) model was used to determine the independent risk factors. Among the 200 patients, 26 patients had difficult intubation with an incidence of 13%. Among different variables, the Mallampati score and NC/TMD were independently associated with difficult intubation. Receiver operating characteristic curve showed a cut-off point of 3 or 4 for Mallampati score and 5.62 for NC/TMD to predict difficult intubation. The diagnostic accuracy of NC/TM ratio and Mallampatti score were better compared to other bedside tests to predict difficult intubation in Indian population.