Preoperative ultrasonographic evaluation of the airway vis-à-vis the bedside airway assessment to predict potentially difficult airway on direct laryngoscopy in adult patients—a prospective, observational study

Background Unanticipated difficult airway remains a challenge for the anesthesiologist with no established standard criteria to predict difficulty in intubation. Our aim was to correlate the pre-anesthetic ultrasonographic (USG) airway assessment parameters with Cormack-Lehane (CL) grade at direct laryngoscopy view under general anaesthesia. This was a prospective, observational study on 150 adult patients between 18 and 70 years with the American Society of Anesthesiologist—Physical Status 1–2 requiring general endotracheal anesthesia for elective surgery. Results The incidence of difficult laryngoscopy was 22.7%. The sonographic distance from anterior neck surface to epiglottis (ANS-E) > 1.67 cm was observed to be a statistically significant USG predictor of difficult laryngoscopic view with sensitivity of 64.71% and specificity of 78.45% ( p = 0.000). The sonographic distance from anterior neck surface to hyoid bone (ANS-H) or to anterior commissure (ANS-AC) did not corelate with difficult laryngoscopy. The ultrasound (US) parameters had higher negative than positive predictive value. Conclusions We found ANS-E distance to be the most significant predictor of difficult laryngoscopy in our study. USG is a useful tool to identify the “at-risk” patients for difficult airway.