Predicting Difficult Intubation in Elective Surgery Patients Through Preoperative Airway Assessment

Abstract

Background: Unanticipated difficult laryngoscopy during elective surgery can lead to hypoxaemia, airway trauma, and perioperative complications; however, no single bedside airway test consistently provides high diagnostic accuracy for preoperative risk stratification. Objective: To evaluate and compare the diagnostic performance of commonly used preoperative airway assessment tests for predicting difficult laryngoscopy in adult elective surgical patients. Methods: A cross-sectional observational study was conducted at the University of Lahore Teaching Hospital among 133 patients aged 18–65 years (ASA I–III) scheduled for elective surgery under general anaesthesia with planned orotracheal intubation. Preoperative assessment included the Modified Mallampati Test (MMT), thyromental distance (TMD), inter-incisor gap (IIG), upper lip bite test (ULBT), LEMON assessment, and atlanto-occipital extension (AOE). Direct laryngoscopy findings were graded using the Cormack–Lehane (CL) system; difficult laryngoscopy was defined as CL grade III–IV. Results: Difficult laryngoscopy occurred in 15/133 patients (11.3%). MMT demonstrated the highest sensitivity (66.7%), while LEMON showed the highest specificity (77.0%). AOE yielded the highest overall accuracy (86.0%) and the strongest association with difficult laryngoscopy (restricted AOE grade III–IV: 12/15 vs 1/118; p<0.001). TMD, IIG, and ULBT showed moderate predictive performance. Conclusion: No single bedside test optimally predicts difficult laryngoscopy; combining complementary assessments, particularly sensitivity-oriented screening with specificity-oriented confirmation and neck mobility evaluation, provides a more reliable preoperative approach.