This prospective observational study aims to evaluate the predictive value of thyromental height (TMH) and ultrasonographic airway measurements in predicting difficult airway in adult patients undergoing elective surgery under general anesthesia.

Preoperative airway assessment will include standard clinical evaluation, TMH measurement, and ultrasonographic measurements of anterior neck soft tissue. Perioperative airway management data, including intubation difficulty, number of attempts, and Cormack-Lehane classification, will be recorded.

The relationship between preoperative measurements and difficult airway will be analyzed to determine their predictive accuracy and clinical usefulness.

Difficult airway management remains a critical issue in anesthetic practice, associated with significant morbidity and mortality. Traditional clinical airway assessment methods have limited sensitivity and specificity in predicting difficult airway. Recently, thyromental height (TMH) and ultrasonographic airway measurements have been proposed as promising tools for improving prediction accuracy.

This prospective, single-center observational study will be conducted in adult patients undergoing elective surgery under general anesthesia. Patients aged 18 years and older with ASA physical status I-III will be included.

Preoperative evaluation will include standard airway assessment methods such as Mallampati score, mouth opening, sternomental distance, and thyromental distance. In addition, TMH will be measured, and ultrasonographic measurements of anterior neck soft tissues will be performed, including skin-to-epiglottis distance, pretracheal soft tissue thickness, and hyomental distance.

Perioperative airway management data will be recorded, including Cormack-Lehane classification, number of intubation attempts, use of adjunct airway devices, and intubation difficulty score.

The primary objective is to evaluate the predictive value of TMH and ultrasonographic measurements for difficult airway. Secondary objectives include assessing their relationship with intubation difficulty, number of attempts, and airway-related complications.

The findings of this study are expected to contribute to improved preoperative airway assessment and safer airway management strategies in clinical practice.

Inclusion Criteria:

Adult patients aged 18 years and older Patients scheduled for elective surgery under general anesthesia Patients requiring endotracheal intubation Patients who provide written informed consent

Exclusion Criteria:

• Patients with known upper airway pathology (e.g., tumor, trauma, infection) Patients with previous head and neck surgery or anatomical deformity affecting airway evaluation Patients with limited mouth opening (<3 cm) or severe cervical spine restriction Patients with contraindications to ultrasonographic examination Patients requiring rapid sequence induction or emergency surgery Patients who refuse to participate

Adult patients undergoing elective surgical procedures under general anesthesia at a tertiary care hospital will be prospectively enrolled. All participants will undergo standardized preoperative airway assessment, including thyromental height measurement and ultrasonographic airway evaluation, followed by perioperative airway management assessment.

Individual participant data (IPD) will not be shared due to institutional policies and protection of patient confidentiality.