Ultrasonographic Parameters in Prediction of Difficult Laryngoscopy in Non-suspected Difficult Airway Patients

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

This study aims to evaluate the ultrasonographic parameters (distance from skin to epiglottis (DSE) and distance from skin to vocal cords (DSVC)) as preoperative predictors of difficult laryngoscopy in non-suspected difficult airway patients undergoing elective surgery.

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.

Inclusion Criteria:

• Aged 18 - 65 years.
• Both sexes.
• Patients who aren't suspected to have a difficult airway after preoperative airway assessment by conventional clinical tests such as modified Mallampati classification (MMC), thyromental distance (TMD), inter-incisor distance (IID), cervical mobility (CM), And neck circumference (NC).
• American society of anesthesia (ASA) I, II, and III physical status.
• Scheduled for elective surgery under general anaethesia.

Exclusion Criteria:

• Patients with maxillofacial injury and airway trauma.
• Patients with a history of previous difficult intubation.
• Patients with anatomical abnormalities.
• Neck scarring, swelling, or burn.
• Pregnancy.
• Obesity.