Use of Ultrasonographic Parameters in Preoperative Prediction of Difficult Laryngoscopy in Non-suspected Difficult Airway Patients Undergoing Elective Surgery; a Prospective Observational Study

Airway management is an integral part of general anesthesia. It simply aims to secure the patient's airway and achieve adequate ventilation and oxygenation for the patient undergoing surgery under general anesthesia. Unsuccessful airway management due to the unexpected difficulty in laryngoscopy is a life-threatening situation and may lead to morbidity and mortality.

Many conventional clinical tests are used in preoperative airway assessment such as modified Mallampati classification, Thyro-mental distance, inter-incisor distance, cervical mobility, and neck circumference, which are used to predict difficulty in the airway, but they have limited value and low sensitivity and specificity. Difficult laryngoscopy cannot be always predicted based on the preoperative assessment by conventional clinical tests. Some patients are thought to have an easy airway by clinical tests, but they show an unexpected difficulty in the laryngoscopy.

The laryngeal view of the patient can be assessed and graded during direct laryngoscopy using the Cormack and Lehane grading scale and its modification that describes the laryngoscopy as easy or difficult.

Ultrasonography is a valuable promising tool for preoperative airway evaluation through identifying important sonoanatomy of the upper airway such as epiglottis, thyroid cartilage, and vocal cords.