With the continuous improvement of medical technology, more and more patients need to undergo surgery as a kind of treatment for their diseases. However, there are various pains that may occur in the perioperative period, risks associated with anesthesia, loss of body organs, surgical trauma, and postoperative procedures Factors such as the onset of the disease can cause the vast majority of patients to have varying degrees of emotional reactions such as worry, worry, nervousness, and fear. Emotional disorders such as depressed mood, disappointed crying, decreased mobility, and delayed thinking and cognitive function, that is, postoperative psychiatric symptoms.

Dexmedetomidine (DEX) is an alpha-2 adrenergic agonist that works by inhibiting norepinephrine. Releasing renaline, which reduces inflammation and thus plays a protective role in the central nervous system. Previous studies have shown that dexmedetomidine is lowering. DEX has the potential to prevent and treat patients undergoing cardiac surgery. The role of postoperative anxiety and depression needs to be further explored for evidence-based evidence. Based on the above research background, the hypothesis of this study is proposed. The intraoperative use of dexmedetomidine has a positive effect on alleviating postoperative anxiety and depression in patients undergoing postoperative cardiac surgery.

1. Observing the effect of intraoperative use of dexmedetomidine on the incidence of postoperative anxiety and depression in patients undergoing cardiac surgery;
2. Observe the effects of intraoperative use of dexmedetomidine on postoperative delirium, quality of life, pain scores, and sleep quality in patients undergoing cardiac surgery;
3. To provide a feasible plan for preventing and treating postoperative anxiety and depression in patients undergoing cardiac surgery, improve the quality of patient prognosis, and reduce the burden on society.

Inclusion Criteria:

1. Age range from 18 to 85 years old, regardless of gender
2. Patients who undergo cardiac surgery on a scheduled basis;
3. ASA level 1-4;
4. Obtain written informed consent form;

Exclusion Criteria:

1. Patients with MMSE scores less than 18 or dementia, intellectual disability, and inability to communicate (coma, severe dementia, hearing or language impairment);
2. Have a history of mental or neurological disorders (such as schizophrenia, epilepsy, Parkinson's disease, or severe myasthenia gravis);
3. Previous history of brain injury;
4. Severe liver dysfunction (Child pugh C-grade) or renal insufficiency (preoperative dialysis);
5. Severe bradycardia (heart rate below 50 beats per minute), pathological sinus syndrome, or atrioventricular block without a pacemaker;
6. Postoperative intensive care unit (ICU) duration exceeding 7 days or death;