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 Mallampatitest in supine patients is doubtful. We undertook this studyto evaluate the efficacy of acromio-axillo-suprasternal notchindex (AASI) for predicting difficult intubation and tocompare it with modified Mallampati test in supine position(MMT-S).Material and Methods: This prospective observationalstudy included 200 patients of American Society ofAnaesthesiologist (ASA) physical status I and II ofeither gender, aged 18-60 years. Patients with anatomicalabnormalities involving head and neck, pregnant, edentulousand BMI>35Kg/m2 were excluded. AASI and MMT-S wereassessed preoperatively. Direct laryngoscopy was performedby an experienced anaesthesiologist blinded to the result ofairway 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 difficultvisualisation of larynx (DVL) and secondary objective was tocompare it with MMT-S. Statistical analysis- McNamer testwas used to compare sensitivity and specificity of both themethods. Comparison of Area under Curve(AUC) of both themethods was performed.Results: AASI was 92% sensitive and 97.71% specificin predicting difficult intubation whereas sensitivity andspecificity of MMT-S was 76% and 84.57% respectively. AreaUnder Curve (AUC) of AASI was 0.97 with cut-off value>0.49 as a predictor of difficult intubation.Conclusion: AASI with cut off value >0.49 has highersensitivity and positive predictive value and is better inpredicting difficult airway in supine patients as compared toMMT-S.