Cough, Postoperative

The goal of this study is to determine whether omitting tracheal suctioning immediately prior to extubation is non-inferior to routine tracheal suctioning with respect to early postoperative oxygenation among adult surgical patients (aged 18-90 years, American Society of Anesthesiologists \[ASA\] physical status I-III) undergoing elective surgery under general anesthesia with endotracheal intubation. The study addresses the following questions: * Primary outcome (non-inferiority): * Is the risk of postoperative desaturation (oxygen saturation \[SpO₂\] \<92% within 60 minutes after extubation) in the no-suction group not worse than in the routine-suction group by more than 10 percentage points? * Secondary outcomes (superiority): * Does omitting tracheal suctioning reduce postoperative cough severity and sore throat? * Does omitting tracheal suctioning avoid increasing extubation-related adverse events? Participants will be randomly assigned (1:1) to one of two groups: * Routine suctioning (SUC): Endotracheal suctioning plus oropharyngeal suctioning immediately before extubation * No suctioning (NON-SUC): Oropharyngeal suctioning only, without endotracheal suctioning All participants will receive standard anesthetic care and postoperative monitoring in the post-anesthesia care unit (PACU) for 60 minutes. Follow-up for airway symptoms and patient satisfaction will be conducted at 24 hours after surgery.