Accuracy of Sternomental Displacement Test and Thyromental Height Test As a Predictive Measure for Difficult Airway in Elderly Surgical Patients: a Prospective Cohort Study

Background Airway assessment before anaesthesia in the elderly is crucial. The delay in endotracheal intubation in this age group can lead to fatal consequences. This study aimed to evaluate the validity of sternomental displacement (SMDD) as a predictor of difficult airway in the elderly and to compare it with the thyromental height test (TMHT).Methods This study included 150 patients aged > 65 years old, ASA i–iii, who were scheduled for elective surgeries under general anaesthesia with endotracheal intubation using conventional laryngoscopy. Cormack–lehane grades iii and iv were assigned as difficult laryngoscopy (DL). Difficult intubation (DI) was defined as insertion of endotracheal tube required more than two attempts or 10 minutes. The primary outcome was the AUROC curve for the SMDD as a predictor of difficult laryngoscopy.Results 14% of our patients showed DL, while 4.7% had DI. SMDD was a good predictor for DL with 0.692 AUC (95% ci: 0.611 − 0.765) at a cut-off value of ≤35 mm, with 71.43% sensitivity, 59.69% specificity, 22.4% PPV and 92.8% NPV. TMHT showed good prediction for DL with 0.794 AUC (95% ci: 0.721–0.856) at a cut-off value of ≤ 49.5 mm. For predicting DI, SMDD showed AUROC (95% ci): 0.814 (0.743–0.873) at a cut-off value ≤35 mm and TMHT had AUROC (95% ci): 0.719 (0.640–0.790) at a cut-off value ≤ 49.5 mm.Conclusion SMDD and TMHT are good objective predictors for DL and di in elderly surgical patients.