Prediction of Difficult Airway Among Patients Requiring Endotracheal Intubation in a Tertiary Care Hospital in Eastern Nepal

Abstract

Introduction: Unanticipated difficult intubation is an undesirable situation. Various bedside screening tests are routinely performed for predicting difficult airway. Although considered a surrogate indicator, difficult laryngoscopy is not the exact measure of intubation difficulty. We aimed to determine the best screening test for predicting difficult laryngoscopy and the association between difficult laryngoscopic view and difficult intubation.

Methods: This prospective, observational study involved 314, ASA I/II adult patients requiring endotracheal intubation for various routine surgical procedures. Sternomental distance < 12 cm, thyromental distance < 6.5cm, inter-incisor distance < 3.5 cm, mandibular protrusion grade 3 and modified Mallampati class III/IV were the predictors of difficult laryngoscopy. Laryngoscopic view was defined as ‘difficult’ when the Cormack and Lehane grade was III/ IV. The sensitivity, specificity, positive and negative predictive values and accuracy of these predictors were compared to find out the best predictor. Requirement of >3 attempts for insertion of the tracheal tube was defined as ‘difficult intubation’. The association between difficult laryngoscopic view and difficult intubation was determined.

Results: The sensitivity of the modified Mallampati class for predicting difficult laryngoscopy was highest (83%). Twelve (3.8%) patients had grade III laryngoscopic view and none had a grade of IV. Intubation was difficult in seven (2.2%) patients. Majority of patients (4 of 7) with difficult intubation had difficult laryngoscopic view (p<0.001).

Conclusions: Modified Mallampati test was better for predicting difficult laryngoscopy compared to other bedside screeing tests. Difficult laryngoscopy could significantly predict difficult intubation in our patients.  

Keywords: Airway evaluation; difficult intubation; difficult laryngoscopy; modified Mallampati class; Nepalese patients; sensitivity.