Role of Acromioaxillosuprasternal Notch Index (AASI) as a New Predictor of Difficult Visualization of Larynx in Comparison with Modified Mallampati Test

Abstract

Background: Pre-operative airway assessment should be able to predict potential difficult airway, allowing management plan to be developed ahead of time. Hence this study was aimed to compare Acromio-AxilloSuprasternal Notch Index (AASI), a new simple bedside test with Modified Mallampati Test (MMP) in predicting difficult visualization of larynx. Materials and Methods: After ethical committee clearance and informed written consent, 320 patients of ASA I and II posted for elective surgery under general anaesthesia were included in this study. AASI and MMP were noted during preanaesthetic airway assessment. After induction of anaesthesia, a blinded and experienced anaesthetist did laryngoscopy, intubated the patient and noted Cormack-Lehane(CL) grading of laryngeal view. The data observed was analysed using Receiver operating characteristic curve(ROC) analysis to compare AASI and MMP. A P value less than 0.05 was considered statistically significant. Results: Incidence of Difficult Visualization of Larynx(DVL) in our study was 8.4%. AASI had better Sensitivity(88.89% v/s 22.22%), Specificity(98.63% v/s 95.22%),Positive predictive value (85.71% v/s 26.32%), Negative predictive value (98.97% v/s 93%) and Diagnostic accuracy(97.81% v/s 89.03%) in comparison with MMP respectively (P <0.001) when cut off reference value of 0.56 AASI was taken. Conclusion: AASI is a better predictor of difficult laryngoscopy with a higher sensitivity and positive predictive value in comparison with MMP. Hence AASI can be used as a simple bedside test to predict difficult airway during pre-anaesthetic airway assessment. Keywords: Acromioaxillosuprasternal notch index (AASI); Modified Mallampati test (MMP); Cormack-Lehane (CL) grade; Difficult visualization of larynx (DVL); Airway assessment.