How to predict difficult tracheal intubation: The application of acromio-axillo-suprasternal notch index

Background: The incidence of difficult laryngoscopy or tracheal intubation is high, which needs a method to predict the difficulty of tracheal intubation to decrease the rate of complications. Therefore, the aim of this study was to evaluate acromio-axillo-suprasternal notch index (AASI) method for predicting difficult tracheal intubation and difficult laryngoscopy.
Materials and Methods: This cross-sectional and diagnostic value study was performed on 108 patients who had indication for endotracheal intubation in the emergency department. Before endotracheal intubation, AASI was evaluated in all patients. The sensitivity, specificity, and total accuracy for predicting the power of AASI for the difficulty of tracheal intubation were measured.
Results: Based on Cormack and Lehane grading system, 54 patients had easy endotracheal intubation (33.3% Grade I and 66.6% Grade II) and 52 patients had difficult endotracheal intubation (57.7% Grade III and 32.7% Grade IV). The sensitivity, specificity, positive predictive value, negative predictive value, and overall accuracy for AASI in cutoff point 0.515 for predicting difficulty of endotracheal intubation with 0.857 area under the receiver operating characteristic curve were 84.6%, 77.7%, 78.5%, 84%, and 81.13%, respectively.
Conclusions: Our results showed that predicting difficulty of endotracheal intubation by AASI is accurate and with high sensitivity and specificity values, therefore, training this method to emergency physicians should be considered in our country or other countries. Further studies are required to confirm our findings.