Comparison of Acromio-Axillo-Suprasternal Notch Index with Combination of Modified Mallampati Score and Thyromental Distance in Predicting Difficult Visualization of Larynx

Abstract

Introduction

Management of the airway is the primary responsibility of the anesthesiologist. Various bedside clinical tests, singly or in combinations are used to predict difficult airway. This study aimed to compare Acromio-axillo-suprasternal notch index with combination of Modified Mallampati score and thyromental distance to predict difficult visualization of larynx by direct laryngoscopy.

Methods

This prospective, analytical study included 142 patients scheduled for elective surgery requiring general anesthesia with endotracheal intubation. Modified mallampati score (MMP), thyromental distance (TMD) and Acromio-axillo suprasternal notch index (AASI) were assessed preoperatively. In operation theatres, laryngoscopy was done and Cormack- Lehane (CL) grading was taken as standard for prediction of difficult visualization of larynx. The sensitivity, specificity, positive predictive value, negative predictive value, accuracy and area under curve (AUC) of AASI was compared with combination of MMP and TMD.

Results

The total incidence of difficult laryngoscopy, defined by CL III and IV was 17.6%. The sensitivity, specificity, PPV, NPV and accuracy of combination of MMP and TMD was 80%, 85.5%, 54.1%, 95.2% and 84.5% respectively (p=0.001).  The sensitivity, specificity, PPV, NPV and accuracy of AASI was 84%, 88.9%, 61.8%, 96.3% and 88% respectively(p=0.001). Likewise, the AUC of AASI was (AUC=0.88; 95% CI, 0.82-0.93, p<0.001) whereas AUC of combination of MMP and TMD was (AUC= 0.82; 95%CI, 0.75- 0.89, p< 0.001) which was comparable.

Conclusion

Acromio-axillo-suprasternal notch index is equivalent to combination of Modified Mallampati score and thyromental distance in predicting difficult visualization of larynx.