Comparison of acromioaxillosuprasternal notch index (a new test) with modified Mallampati test in predicting difficult visualization of larynx

Abstract

Background: We aimed to compare the efficacy of a new bedside screening test named acromioaxillosuprasternal notch index (AASI) with modified Mallampati (MMP).

Methods: A total of 603 adult patients, who were candidates for tracheal intubation in elective surgery, were enrolled in this prospective study. Preoperative airway assessment was carried out with AASI and MMP. The new AASI score is calculated based on the following measurements: (1) using a ruler, a vertical line is drawn from the top of the acromion process to the superior border of the axilla at the pectoralis major muscle (line A); (2) a second line is drawn perpendicular to line A from the suprasternal notch (line B); and (3) the portion of line A that lies above the point where line B intersects it is line C. AASI is calculated by dividing the length of line C by that of line A (AASI = C/A). After induction of anesthesia, the laryngeal view was recorded according to the Cormack-Lehane grading system. Receiver operating characteristic curve analysis was employed to compare between AASI and MMP.

Results: Difficult visualization of larynx (DVL, Cormack-Lehane III and IV) was observed in 38 (6.3%) patients. The best cutoff point for DVL was defined at AASI > 0.49. AASI had a lower false negative rate and higher predictive values (sensitivity, positive predictive value, and accuracy) in comparison with MMP.

Conclusion: AASI was associated with higher predictive values than MMP and could be used for estimation of DVL.

Keywords: anesthesia; intratracheal; intubation; laryngoscopy.