Is Acromio-Axillo-Suprasternal Notch Index a Reliable Test to Predict Difficult Tracheal Intubation in Adults in Supine Position - an Observational Study

Abstract

Introduction: The applicability of the Modified Mallampati test in supine patients is doubtful. We undertook this study to evaluate the efficacy of acromio-axillo-suprasternal notch index (AASI) for predicting difficult intubation and to compare it with modified Mallampati test in supine position (MMT-S). Material and Methods: This prospective observational study included 200 patients of American Society of Anaesthesiologist (ASA) physical status I and II of either gender, aged 18-60 years. Patients with anatomical abnormalities involving head and neck, pregnant, edentulous and BMI>35Kg/m 2 were excluded. AASI and MMT-S were assessed preoperatively. Direct laryngoscopy was performed by an experienced anaesthesiologist blinded to the result of airway assessment tests. Cormack Lehane grade (CL grade) and number of attempts to successful intubation were noted. Primary objective was to assess AASI as predictor of difficult visualisation of larynx (DVL) and secondary objective was to compare it with MMT-S. Statistical analysis-McNamer test was used to compare sensitivity and specificity of both the methods. Comparison of Area under Curve(AUC) of both the methods was performed. Results: AASI was 92% sensitive and 97.71% specific in predicting difficult intubation whereas sensitivity and specificity of MMT-S was 76% and 84.57% respectively. Area Under Curve (AUC) of AASI was 0.97 with cutoff value >0.49 as a predictor of difficult intubation. Conclusion: AASI with cut off value >0.49 has higher sensitivity and positive predictive value and is better in predicting difficult airway in supine patients as compared to MMT-S.