Relationship of Isthmus Thickness With Difficult Laryngoscopy and Difficult Intubation in Patients Receiving Hypothyroidism Treatment

The neck skin thickness from the thyroid isthmus to the skin will be measured in millimeters using a linear ultrasound probe (3-13 Hz) in the supine position with neck hyperextension. Measurements will be taken in a transverse view at the level of the 2nd-3rd tracheal rings, and the average of three measurements will be recorded.