Effectiveness and Validity of Preoperative Ultrasonographic Airway Assessment and Clinical Screening Tests to Predict Difficult Laryngoscopy: A Prospective, Observational Study

The anticipation of a challenging airway can be demanding in emergency care settings. Due to the patient's clinical condition, executing the pre-intubation clinical screening tests during the management of the airway in an emergency situation can be sometimes troublesome. Ultrasonographic airway assessment may become a helpful tool, but no specific sonographic measurements can precisely visualize the prospect of meeting a difficult airway. Therefore, the present study aimed to verdict some correlation between preoperative sonographic airway assessment parameters and the Cormack-Lehane (CL) grading at laryngoscopic view in patients undergoing general anesthesia with endotracheal intubation.

This observational study was conducted on 150 elective surgery subjects undergoing general anesthesia. The clinician in the pre-anesthetic clinic performed clinical airway and ultrasonographic airway assessments to predict difficult intubation and correlated with the CL grade viewed at laryngoscopy in the operative room during intubation. The parameters assessed were sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV).

In this study, the incidence of difficult intubation was 13.3%. The Mallampatti Grading (MPG) showed the maximum receiver operating characteristic (ROC) and area under the curve (AUC) among the clinical predictors, with 86.7% sensitivity. At the same time, the skin-to-hyoid distance has the maximum ROC among the sonographic parameters, and the skin-to-thyroid isthmus has the utmost sensitivity to predict difficult laryngoscopy.

Among the clinical predictors, MPG and the sonographic parameters, like the skin-to-hyoid distance and skin-to-thyroid isthmus, are favorable predictors of difficult laryngoscopy.