This trial is going to evaluate the safety and effectiveness of intranasal DEX(dexmedetomidine) in breast lumpectomy under local anaesthesia,and to investigate the optimal dose of intranasal DEX in breast lumpectomy.

Breast lumpectomy associated with a high level of anxiety, fear and pain requires fast and effective anaesthesia techniques. Presently, this procedure is usually performed under general or local anaesthesia. General anaesthesia provides an effective sedation; however, for minor procedures, general anaesthesia is resource-intensive and postoperative complications, such as nausea, vomiting or extended time to ambulation, are more likely. Local anaesthesia alone may be uncomfortable or uncooperative for patients. Therefore, an efficient drug regimen is required that reduces analgesic consumption, minimises opioid-related side effects and shortens post-anaesthesia care unit (PACU) stay following surgery.

Dexmedetomidine (DEX) is a highly selective α2 adrenoreceptor agonist that provides sedation without respiratory depression. Its sedative, anxiolytic, analgesic and haemodynamic effects have made it a useful adjunct to anaesthesia and sedation. DEX may provide a conscious sedation under monitored anaesthesia care (MAC) that is a logical middle ground between general anaesthesia and local anaesthesia. Intranasal DEX was recently shown to provide satisfactory anaesthesia and premedication sedation in healthy volunteers and paediatric patients. The intranasal route is not only effective, but also well-tolerated and convenient This trial is going to evaluate the safety and effectiveness of intranasal DEX(dexmedetomidine) in breast lumpectomy under local anaesthesia, and to investigate the optimal dose of intranasal DEX in breast lumpectomy.

Inclusion Criteria:

• with ASA(American Society of Anesthesiologists) physical status I and II
• scheduled for breast lumpectomy

Exclusion Criteria:

• a history of heart block
• upper respiratory tract infection
• asthma
• allergy to DEX or local anaesthetics
• memory or cognitive dysfunction
• pregnancy
• lack of understanding the consent process
• impaired liver or renal function
• a history of drug or alcohol abuse