Comparison of Different Ultrasound Parameters for Airway Assessment in Patients Undergoing Surgery under General Anaesthesia.

Aims: The aim of this study was to evaluate and correlate ultrasound measurement of airway parameters with the Cormack- Lehane (CL) grading observed under direct laryngoscopy for prediction of difficult airway.

Methods: This prospective, observational study was conducted in a tertiary care institute. Ninety-six patients were scheduled for elective surgery under general anaesthesia and tracheal intubation. They were categorised as having easy (CL grades 1, 2a, and 2b) or difficult (CL grades 3a, 3b, and 4) laryngoscopy. The sonographically measured airway parameters included anterior neck soft tissue thickness at vocal cord level (ANS-VC), hyomental distance ratio (HMDr), and tongue volume (TV). These parameters were compared and correlated with the CL grading. The statistical analysis was done using SPSS version 21.0.

Results: Difficult laryngoscopy was observed in 17.7% patients. Significant difference was noted in ANS-VC 0.28 6 0.09; 0.39 6 0.12, (P < .0001) and HMDr, 1.2 6 0.09; 1.15 6 0.13, (P ¼ .006) for easy and difficult laryngoscopy, respectively. ANS-VC had a sensitivity of 78.9% and specificity of 71.1% (AUC-0.816) followed by HMDr (AUC-0.713) and TV (AUC-0.608). Combined ultrasound parameters had significantly higher AUC value (0.867).

Conclusions: ANS-VC was the most significant parameter with a value of >0.29 cm being a sensitive predictor of difficult intubation. Combined sonographic parameters (ANS-VC, HMDr, and TV) were better predictors of difficult intubation.