Chronic postoperative pain (CPSP) is common symptom in patients after surgery, seriously affected the quality of life. Accumulating evidences have demonstrated dexmedetomidine can improve chronic pain. However, the prevention of dexmedetomidine on CPSP remain uncertain.

Chronic postoperative pain (CPSP) is defined as pain persisting at least 3 months after surgery. It is most common in patients who undergoing breast or thoracic surgery. Dexmedetomidine, a adrenergic α2 agonists, can alleviate the postoperative pain 24 h after surgery. In our study, patients were randomly assigned to one of the two group to receive 0.5mg/kg/h infusion dexmedetomidine (Group D, n=57) or normal saline (Group C, n=57). The pain scales were evaluated day 1, day 2, day 3, month 3, month 6 after surgery.

Inclusion Criteria:

• Patients must have been 18 to 65 yr old, and been scheduled for breast or thoracic surgery.

Exclusion Criteria:

• Patients with limitations of self-expression or visual dysfunction or having emergency surgery, a severe psychiatric illness, or chronic pain problems in the chest area for longer than 2 months before the surgery,or patients who could not provide informed consent were excluded.
• Pregnant women and prisoners were also excluded.