Clinical Research Directory

Inclusion Criteria: * American Society of Anesthesiologists (ASA) physical status II-III. * Age ≥ 65 years, with no gender restriction. * Patients scheduled for elective thoracoscopic lung resection under general anesthesia, with an expected operative duration of 1-4 hours. * Body mass index (BMI) between 18 kg/m² and 30 kg/m². Exclusion Criteria: * Known hypersensitivity to dexmedetomidine hydrochloride or any of the excipients in the investigational product. * Pre-existing nasal conditions, nasal surgery, or nasal allergies that may significantly impair nasal drug absorption (e.g., chronic nasal congestion, rhinorrhea, epistaxis, nasal anatomical abnormalities, or mucosal pathology affecting absorption). * History of cranial trauma. * Pre-existing diagnosis or clinical suspicion of neurocognitive impairment, defined as a Mini-Mental State Examination (MMSE) score \< 24. * History of schizophrenia, epilepsy, Parkinson's disease, or myasthenia gravis. * History of alcohol or substance abuse/dependence. * Left ventricular ejection fraction \< 30%; sick sinus syndrome; severe sinus bradycardia (\< 50 bpm); or second- or higher-degree atrioventricular block without permanent pacemaker implantation. * History of myocardial infarction, unstable angina, severe cardiac arrhythmia, or decompensated cardiac insufficiency. * Asthma, emphysema, chronic bronchitis, or chronic obstructive pulmonary disease (COPD) considered inappropriate for study participation by the investigator. * Severe hepatic impairment (Child-Pugh Class C). * Severe renal dysfunction requiring preoperative dialysis. * Inability to provide valid informed consent due to cultural background, language barrier, or cognitive impairment. * Refusal to sign the informed consent form. * Other conditions deemed inappropriate for study participation by the investigator.