Original article / research
Comparison of Acromio-Axillo-Suprasternal Notch Index with Upper Lip Bite Test to Predict Difficult Visualisation of Larynx: A Prospective Observational Study
UC01-UC05
Correspondence
Dr. DR Binay Teja Reddy,
H. No. 12-11-1528, Boudhanagar, Warasiguda, Opp. Arts College Railway Station,
Secunderabad, Hyderabad-500061, Telangana, India.
E-mail: binayteja15@gmail.com
Introduction: Preoperative prediction of Difficult Visualisation of Larynx (DVL) remains a critical aspect of safe anaesthetic practice. Failure to anticipate airway difficulty leads to serious complications. Various bedside airway assessment tests like the Upper Lip Bite Test (ULBT) are widely used, but none provide complete reliability. The Acromio-Axillo-Suprasternal Notch Index (AASI) is a newer anatomical parameter proposed to improve predictive accuracy.
Aim: To compare the diagnostic performance of AASI and ULBT to predict DVL in adult patients undergoing elective surgery under general anaesthesia.
Materials and Methods: This single-blinded prospective observational study was conducted in the Department of Anaesthesiology at Smt. BKS Medical Institute and Research Centre, Sumandeep Vidyapeeth Deemed to be University, Vadodara, Gujarat, India. The study included 166 patients aged 18-60 years, classified as American Society of Anaesthesiologists (ASA) I-III, scheduled for elective surgeries. Patients with Body Mass Index (BMI) ≥35 kg/m², airway deformities, or emergency conditions were excluded. Preoperative airway assessment was performed using ULBT and AASI (cut-off ≥0.49). Following induction of anaesthesia, direct laryngoscopy was performed and graded using the Cormack-Lehane (CL) classification. Grades I-II were considered easy and Grades III-IV as DVL. Quantitative data were analysed using the independent student’s t-test, qualitative data using the Chi-square test, and the diagnostic validity of AASI and ULBT was assessed by sensitivity, specificity, Positive Predictive Value (PPV), Negative Predictive value (NPV), and accuracy.
Results: Out of 166 patients, 23 (13.86%) had DVL. Mean age and gender distribution was comparable between two groups (38.44±10.89 vs 40.53±11.09, p=0.24), (p-value=0.25). There were no significant differences in mean weight, height, or BMI between groups (p-value >0.05). Distribution of ASA grades also did not differ significantly (p-value=0.08). AASI demonstrated sensitivity of 60.87%, specificity of 91.61%, PPV of 53.85%, NPV of 93.57%, and accuracy of 87.35%. ULBT showed sensitivity of 47.83%, specificity of 90.21%, PPV of 44.00%, NPV of 91.49%, and accuracy of 84.34%.
Conclusion: AASI is a superior predictor of DVL compared to ULBT, with higher sensitivity, specificity, and overall diagnostic accuracy. Its high negative predictive value makes it a useful screening tool in clinical practice. However, as no single test is completely reliable, combining AASI with other airway assessment methods may further enhance prediction and improve patient safety.