Emergence agitation is one of the common postoperative complications after functional endoscopic sinus surgery（FESS). The objective of present study is to explore the effectiveness of butorphanol in the alleviation of emergence agitation in patients undergoing Functional Endoscopic Sinus Surgery.

Butorphanol is a mixed agonist-antagonist opioid with strong κappa-receptor agonist and weak mu-receptor antagonist activity. It is commonly used for the management of cancer, postoperative, gynecologic, and obstetric pain. Additionally, Butorphanol has less respiratory depression and sedation effects, which make it may become a good medicine to alleviate the agitation. However, there is no clinical evidence to confirmation of such effectiveness of butorphanol. The objective of present study is to explore the effectiveness of butorphanol in the alleviation of emergence agitation in patients undergoing Functional Endoscopic Sinus Surgery.

Inclusion Criteria:

1. Age >=18 years,<=65years;
2. height 150-180 cm;
3. weight 55-80 kg;
4. Signed the inform consent
5. American Society of Anesthesiologists classification I to II
6. Select to functional endoscopic sinus surgery

Exclusion Criteria:

1. Existing cerebral disease, or have a history of neurological and psychiatric diseases including Alzheimer Disease, stroke, epilepsy and psychosis;
2. Several audition or vision disorder;
3. Unwillingness to comply with the protocol or procedures.
4. Can not communicated with Chinese Mandarin
5. Existing bradycardiac arrhythmia（Heart rate <60 bpm for any reasons）
6. Existing gastrointestinal ulcer
7. Existing urinary incontinence
8. Existing asthma or chronic obstructive pulmonary disease
9. Allegory to Butorphanol