Magnitude and Predisposing Factors of Difficult Airway during Induction of General Anaesthesia.

OBJECTIVE: To assess magnitude and predisposing factors of difficult airway during induction of general anaesthesia.

METHODS: Hospital based cross sectional study carried out to determine the incidence of difficult mask ventilation, difficult laryngoscopy (Cormack and Lehane III and IV), difficult intubation (IDS ≥ 5), and failed intubation. The association between each predisposing factor and airway parameters with components of difficult airway is investigated with binary logistic regression. Sensitivity, specificity, positive and negative predictive value of the test, and odds ratio with 95% confidence interval were calculated to determine the association between independent and dependent variable.

RESULT: The incidence of difficult laryngoscopy, difficult intubation, and failed intubation are 12.3%, 9%, and 0.005%, respectively. Mouth opening < 30 mm and Mallampati classes III and IV are the most sensitive tests and second high specific test next to combination of tests to predict difficult intubation and laryngoscopy ( P value < 0.001). Unrestricted multiple attempt without alternative airway techniques resulted in exponential increase in desaturation episodes and further difficulty of airway management ( P value < 0.001).

DISCUSSION AND CONCLUSION: Mallampati classes III and IV, mouth opening ≤ 30 mm, jaw slide grade C, attempt > 3, and ineffective alternative technique have increased predictability value of difficult airway.