Evaluation Of Efficacy Of Ultrasonographic Airway Parameters For Predicting Difficult Airway In Patients Undergoing Elective Surgery Under General Anesthesia – A Prospective Observational Study

Abstract

ABSTRACT Background and Aim: The sonographic assessment of airway in the preoperative period has encouraging results in predicting difficult laryngoscopy. Materials and Methods: A prospective, observational study involving 174 patients who were scheduled for elective surgery that required tracheal intubation and general anaesthesia was carried out. Sonographic measurements were made of the pre-epiglottic space (Pre-E) depth and the E-VC (the midpoint of the vocal cord distance) between the epiglottis and the vocal cords. Similar to this, the head was placed in neutral and extended postures while the Hyomental distance ratio (HMDR) was determined sonographically. Pre-E/E-VC, HMDR's ability to predict difficult laryngoscopy (Cormack-Lehane [CL] Grade 3, 4) was the main aim. Correlating these metrics with CL grade was the secondary aim. Results: Intubation difficulties were noted in 17.8% of patients. The mean ± standard deviation (SD) of the Pre-E/E-VC ratio was 1.25±0.38 for easy intubation (CL grade1,2) and 1.95±0.20 for difficult intubation (CL Grade 3 and 4) (P < 0.001). The HMDR mean ± SD for easy intubation was 1.30±0.05 (CL Grades 1, 2), and 1.16±0.05 (CL Grades 3 and 4) for difficult intubation (P < 0.001). When it came to predicting difficult laryngoscopy, pre-E/E-VC ratios greater than 1.90 cm showed an 92% sensitivity and an85 % specificity, while HMDR values less than 1.16 had an 70% sensitivity and an 85% specificity (P < 0.001). Conclusion: Compared to HMDR, the sonographic measurement of the Pre-E/E-VC ratio is a more accurate predictor of CL grading. Pre-E/E-VC ratio more than 1.90 corresponds to difficult laryngoscopy (CL Grade 3,4). Pre E/E-VC ratio can be used for accurately predicting CL grading than HMDR. Therefore, to predict a problematic airway, ultrasonography should be included in routine pre-anaesthetic examinations. Pre-E/E-VC and HMDR are useful indicators for predicting difficult airways.