Inhaling Penehyclidine to Prevent Perioperative Respiratory Adverse Events in Children at Risk Undergoing Sevoflurane Anesthesia

Inclusion Criteria: 1. Pediatric patients aged 3 to 7 years. 2. Scheduled to undergo ophthalmic surgery. 3. Judged to be at risk of PRAEs (with at least one parentally reported risk factor for the PRAEs, including history of a recent cold, wheezing during exercise, wheezing more than three times in the past 12 months, nocturnal dry cough, eczema, or a family history of asthma, rhinitis, eczema, or exposure to passive smoke). Exclusion Criteria: 1. American Society of Anesthesiologists (ASA) physical classification ≥ IV. 2. Known cardiopulmonary diseases (eg. uncorrected congenital heart disease, primary or secondary pulmonary hypertension, tumors, or structural lung diseases). 3. Severe renal dysfunction (requirement of renal replacement therapy) or severe hepatic dysfunction (Child-Pugh grade C); 4. Neurological disorders. 5. Neuromuscular diseases. 6. Contraindication for PHC. 7. Inhalation of β2-receptor activator, M-receptor blockers and/or glucocorticoids within 1 month before surgery. 8. Allergy to anticholinergic drugs. 9. Use of endotracheal tube (ETT) for ventilation. 10. Known difficult airway. 11. Severe upper respiratory tract infections (URTIs) and the anesthesiologist recommended delaying surgery. 12. Participation in other clinical trial during the last month or within the six half-life periods of the study drug used in the last trial. 13. Parents refusing to allow their children to participate. 14. Obesity, with a body mass index (BMI) over 95th percentile according to the WHO guideline.