Evaluation and comparison of sonographic difficult airway assessment parameters with clinical airway predictors

None of the clinical difficult airway predictors are 100% sensitive and specific. Ultrasound is being used for airway assessment, but there is still no established parameters or model to predict difficult laryngoscopy. This observational study was planned to determine the predictive ability of clinical and sonography-based airway assessment parameters for difficult laryngoscopy and intubation.

A total of 130 patients of 18-60 years of age undergoing elective intubation were included. The distribution of Cormack-Lehane (CL) grade and intubation difficulty scale (IDS) was correlated with the clinical and sonographic screening parameters for difficult airways.

The prevalence of difficult laryngoscopy and difficult intubation in our study was 17.6% and 11.5%, respectively. Mallampati grade (MMG), upper lip bite test (ULBT), neck circumference, hyomental distance ratio (HMDR), tongue thickness (TT), skin to epiglottis/epiglottis to vocal cord distance (SED/E-VC), and mandibular condylar mobility (MCM) had significant association with the difficult laryngoscopy and MMG, neck circumference, SED, SED/E-VC; MCM had significant association with the difficult intubation. The combination of these predictors showed better diagnostic ability for difficult airways. Model 1 based on ultrasound parameters showed an area under the curve (AUC) of 0.848 (CI- 0.748-0.947, P value < 0.0001) and model 2 based on combined clinical and ultrasound parameters showed an AUC of 0.755 (95% CI- 0.631-0.879, P value < 0.0001).

Ultrasound-based airway predictors can help in predicting difficult laryngoscopy and intubation along with the clinical parameters. Individual sonographic predictors have moderately satisfactory diagnostic profiles. The models based on combined tests have better diagnostic value.