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Correlation of anticipated difficult airway with concurrent intubation: A prospective observational study

Background: Neither all anticipated difficult airways prove to be difficult intubations nor can all difficult intubations be accurately predicted. We conducted this prospective observational study to evaluate the incidence of anticipated difficult airway and concurrent difficult intubation and look for any correlation between them. Patients and Methods: In this study, 352 patients aged >18 years posted for elective surgery requiring general anaesthesia with the placement of endotracheal tube were recruited after obtaining the Ethical Committee approval and written informed consent. The airway was examined at the time of preanaesthetic check up and assigned the modified Mallampati class and Wilson's score. The modified Mallampati Class III/IV and Wilson's score of >4 were considered a difficult airway. Concurrent intubation was graded according to the Cormack–Lehane classification on laryngoscopy. Other parameters such as the duration of laryngoscopy, time taken for intubation and number of attempts were also noted. The incidence of anticipated and unanticipated difficult airway was calculated separately for each score along with its sensitivity, specificity, positive predictive value and negative predictive value. The significance of this association was analysed using the Chi-square test. Results: The incidence of the anticipated difficult airway by the modified Mallampati classification was 6.8%, whereas that by Wilson's score was 2.5%. The incidence of actual difficult intubation was 13%. Actual difficult airways out of those anticipated by the modified Mallampati classification were only 8, whereas those anticipated by Wilson's score were 27. Correlation between them was calculated using the Chi-square test with P