To investigate the effects of sevoflurane on respiratory parameters and respiratory inflammation in healthy and RSV-infected under general anesthesia and to propose suitable perioperative airway protection measures for children with respiratory virus infection undergoing general anesthesia.

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.

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