Clinical Research Directory

Inclusion Criteria: * Age 5-9 years; * elective adenoidectomy, tonsillectomy, or adenotonsillectomy operation * ASA physical status I-II; * surgery planned under general anesthesia; * able to undergo standard endotracheal intubation and standard anesthetic protocol -; no dermatologic or cardiac barrier to preoperative Holter monitoring; * written informed consent provided by parent/legal guardian. Exclusion Criteria: * ASA physical status III or higher; congenital heart disease, arrhythmia, or cardiac conduction disorder; * known neurologic disease (e.g., epilepsy or cerebral palsy); * psychiatric diagnosis; * chronic inflammatory or immune-system disease; * acute infection within 2 weeks before surgery * regular steroid, immunosuppressive, or anti-inflammatory medication use; * endocrine disease such as uncontrolled thyroid disease; * preoperative hemodynamic instability; * major unexpected intraoperative complication or ICU requirement; * intraoperative atropine, lidocaine, beta-blocker, or epinephrine use; * history of prematurity or syndromic disease; * parent/legal guardian declines consent.