Ultrasound Evaluation of Anterior Neck Soft-Tissue Thickness to Predict Difficult Intubation in Overweight Adult Patients Posted for Surgery under General Endotracheal Anesthesia - An Observational Study.

Background: Ultrasonographic imaging has been recently become simple portable and non-invasive adjuvant for bedside assessment of anterior neck soft tissue thickness which when measured at different levels showed to have significant role in predicting difficult laryngoscopy.

Aims and objectives: Primary objective was Ultrasonographic measurement of anterior neck soft tissue thickness at 3 levels -Distance from skin to hyoid bone (DSHB) -Distance from skin to thyrohyoid membrane (DSTM) -Distance from skin to anterior commissure of vocal cord(DSAC) and to compare and correlate the findings with Cooks modification of Cormack-Lehane score in predicting difficult laryngoscopy. Secondary objective was to compare and correlate the ultrasonographic measurements with conventional airway assessment methods.

Materials and methods: After obtaining approval from the ethical committee, 90 Patients with BMI above 25 kg /m2 was enrolled for the study. A day before the surgery a thorough Preanaesthetic evaluation and assessment of the airway is done using conventional methods. Then on the day of surgery ultrasonographic measurement of anterior neck at 3 levels was done and after inducing the patients laryngoscopy was done and Cooks modification of Cormack-Lehane score assessed.

Results: The optimal cut off values to predict difficult laryngoscopy was 1.26, 2 and 1.2 cms for DSHB, DSTM and DSAC respectively, and among the three skin to anterior commissure of vocal cord was observed to be best USG parameter with more area under the ROC curve.

Conclusion: USG measurement of anterior neck soft tissue thickness can be useful in predicting difficult laryngoscopy in overweight and obese patients also it had more diagnostic accuracy than conventional methods like MMS in predicting difficult laryngoscopy.