Validity of Ultrasound in Correlation with Cormack-Lehane Grading in Obese Patients: A Cross-Sectional Study

Abstract

Background: Ultrasound (US) of the upper airway has the potential to be a valuable addition to traditional clinical evaluation methods. Objectives: This work aimed to assess the validity of US in correlation with Cormack-Lehane grading (CLG) in obese patients. Methods: This cross-sectional work was performed on 78 patients ranging in age between 21 and 60 years, both genders with the American Society of Anesthesiologists (ASA) II-III individuals and body mass index (BMI) 30 kg/m² or more, under general anesthesia with endotracheal tube placement. Each separate finding by the US and conventional clinical airway assessment methods before anesthesia induction correlated to the CLG of the same patient after the induction of anesthesia. Grades III and IV are categorized as difficult laryngoscopy. Results: A significant positive association existed among CLG and duration of US measures, pre-epiglottis spaces (Pre-E) ratios, to the distance between a point mid away vocal cords and epiglottis, Pre-E, ratio of hyomental distance extension/hyomental distance neutral and Mallampati; however, there was a significant negative correlation with skin to anterior commissure, hyomental distance extension, hyomental distance neutral, sternomental distance, and thyromental distance (P < 0.05). The ratio between Pre-E over the distance between the epiglottis and a point midway through the vocal cords at cut-off > 2.23 can discriminate difficult laryngoscopy with sensitivity 100% and specificity 100% and area under the curve of 1. Conclusions: The sonographic assessment of the upper airway aids in predicting individuals who might have challenges with airway management. A reliable indicator of a challenging laryngoscopy was the sonographic parameter ratio of Pre-E to the distance between the vocal cords' midway point and the epiglottis.