The Effect of Sevoflurane on Airway Hyperreactivity During the Perioperative Period.

Inclusion Criteria: 1. Patients voluntarily joined this study and signed an informed consent form； 2. Age: 2-5 years old； 3. The patient should have a good general condition and no serious internal medicine comorbidities (ASA classification of the American Anesthesiology Association is Grade I); BMI ≤ 20; 4. Plan to undergo elective adenoidectomy or adenotonsillectomy with tracheal intubation. Exclusion Criteria: 1. Children with a history of allergic asthma; 2. Children with space-occupying lesions of the chest and lungs, or acute bronchiolitis or pneumonia; 3. Children with cardiovascular diseases that may cause cough, wheezing, and other symptoms; 4. Children who used leukotriene modulators, β2 receptor agonists, anticholinergics, theophyllines, or hormonal treatment drugs within two weeks; 5. Children allergic to propofol, sevoflurane, or other anesthetic agents; 6. Children with a family history of malignant hyperthermia; 7. Children with liver and kidney dysfunction; 8. The result of rapid antigen detection and nucleic acid test for RSV was inconsistent, or children combined with pathogen infections other than RSV; 9. Children with fever.