Comparison of Ultrasound, CT, and Classical Methods for Selecting Sizes and Placement of Left-Sided Double-Lumen Tubes

Inclusion Criteria: * Requiring lung isolation in thoracic surgery, * American Society of Anesthesiologists (ASA) risk score of 1-2-3, * Patients who are literate and able to provide informed consent Exclusion Criteria: * Patients with an ASA score of 4 or higher, * Criteria for difficult intubation, * Difficulty in mouth opening, small jaw deformities, * Abnormal cricoid cartilage appearance, * A history of laryngeal or neck surgery, * Preoperative throat pain and hoarseness, * Tumors and deformities in the main airway