Efficacy of Upper Airway Angle and Glottic Height in Unanticipated Difficult Laryngoscopy Prediction

Upper Airway Angle and Glottic Height in Unanticipated Difficult Laryngoscopy Prediction

Abstract

Unanticipated difficult laryngoscopy is a significant problem in airway management and is linked to higher morbidity. Objectives: To determine the diagnostic accuracy of upper airway angle and glottic height to predict unanticipated difficult endotracheal intubation, taking Cormack–Lehane classification as the gold standard. Methods: This study was a cross-sectional research work conducted at Sindh Institute of Urology and Transplantation, Karachi, during the period of six months from 7 August, 2025 to 31^st January, 2026. A sample size of 150 patients aged between 18 and 80 years, subjected to general anesthesia with direct laryngoscopy, was included. The 2 x 2 contingency tables were used to calculate the diagnostic accuracy indices, and the effect modifiers were stratified; an independent t-test was used, where p≤0.05 was regarded as significant. Results: UAA showed a sensitivity of 73.7%, a specificity of 85.7%, a PPV of 63.6%, an NPV of 90.6%, and a total accuracy of 82.7%. The sensitivity of GH was 78.9%, specificity was 78.5%, PPV was 55.6%, NPV was 91.7%, and accuracy was 78.7%. Conclusions: UAA and GH are non-invasive and easy to use and predict difficult laryngoscopy, especially because they show high negative predictive values. These measurements of the anatomy should be considered in the standard airway evaluation to improve preoperative prediction and patient safety.