A prospective observational study to predict difficult intubation using simple non-invasive tests

Introduction: Airway assessment is the first step in successful airway management. Several anatomical and functional maneuvers can be performed to estimate the difficulty of endotracheal intubation. We aimed to elucidate the role of upper lip bite test (ULBT), hyomental/thyrosternal (HMD/TSD) distances, the mandible length (ML) and their correlation in predicting difficulty intubation in relation to laryngoscopic view as per Cormack Lehane (CL) grading. Methods: After institutional approval informed consent obtained from160 consecutive patients aged between 20 to 60 years of ASA grading I and II scheduled for elective surgical procedures requiring tracheal intubation and meeting the inclusion criteria were enrolled in this study. Each patient was evaluated regarding ULBT, HMD, TSD, ML. Larngoscopy was assessed and findings were graded according to Cormack and Lehane's grading system. Results: The above study states the Negative Predictive Value (NPV) and Positive Predictive Value (PPV) of ULBT were found to be 86.7% and 94.5% respectively. Specificities of ULBT, HMD, TSD and ML were found to be 98.6%, 97.8%, 96.4% and 97.8% respectively. Diagnostic accuracy of ULBT, HMD, TSD, ML were found to be 93.8% ,88.1% ,84.4% and 91.3% respectively. Conclusion: It concludes that high specificity, NPV, PPV and Accuracy of ULBT as revealed in this study could be good rationale for its application in the prediction of difficulty or easiness in the intubation.