Comparing " Acromio-Axillo-Suprasternal Notch Index (AASI)" as a New Screening Test for Predicting Difficult Laryngoscopy with Four Commonly Used Tests

Prediction of difficult laryngoscopy is an essential part of airway management in general anesthesia .The purpose of the present study was comparison of commonly used tests of prediction of difficult laryngoscopy and endotracheal intubation ratio of height to thyromental distance (RHTMD), Modified Mallampati test (MMT), upper lip bite test (ULBT), ratio of neck circumference to thyromental distance (NC/TMD) with acromio-axillo-suprasternal notch index (AASI) in general anesthesia.
A total of 728 patients scheduled for surgery under general anesthesia with endotracheal intubation were enrolled in this study. The dimensional predictive test measurements (AASI, ULBT, RHTMD, NC/TMD, MMT) were accomplished on all patients. The laryngoscopic view was graded with Cormack-Lehane (CL) grading system. Receiver operating characteristic (ROC) curve, Sensitivity, specificity, and Positive predictive value (PPV) were used to compare the tests.
Findings: Our study showed that the incidence of difficult view laryngoscopy (DVL) is about 2.9%. AASI had the highest specificity, positive likelihood ratio, PPV and NPV in comparison with the other predictive tests. AASI with cutoff point ≤ 0.6 had the higher cut off point. AASI has the highest ROC with significant difference to other prediction tests. RHTMD had the least sensitivity.
Our study showed that AASI can be a good screening test to predict difficult laryngoscopy in general anesthesia.