Impact of Perioperative Dexmedetomidine and Esketamine on Postoperative Quality of Recovery

Inclusion Criteria: * Aged 18 years or over; * Scheduled to undergo surgery under general anesthesia, with an expected surgical duration of at least 1 hour; * Required patient-controlled intravenous analgesia after surgery. Exclusion Criteria: * Unable to communicate preoperatively due to visual, auditory, or verbal barriers or other reasons; * Severe bradycardia (heart rate \<50 bpm), sick sinus syndrome, or grade 2 or higher atrioventricular block without pacemaker; * History of hyperthyroidism or pheochromocytoma; * History of schizophrenia, epilepsy, Parkinson's disease, myasthenia gravis, or intracranial hypertension; * Intracranial tumor or neurosurgery; * Severe liver dysfunction (Child-Pugh class C), renal failure (requiring renal replacement therapy), or American Society of Anesthesiologists class IV or higher; * Enrolled in other clinical studies.