Dexmedetomidine Dose-Dependent on Lung Function and AQP1 in One-Lung Ventilation Surgery

Inclusion Criteria: * American Society of Anesthesiologists (ASA) physical status I or II * Age 40-70 years * Body mass index (BMI) 18-30 kg/m² Exclusion Criteria: * Preoperative tumor radiotherapy or chemotherapy * Immune or endocrine disorders * Hepatic or renal dysfunction * Preoperative corticosteroid use * Recent respiratory infection or chronic lung disease * Sick sinus syndrome or atrioventricular block * Preoperative anemia (hemoglobin \< 90 g/L)