Excitement during the emergence from general anesthesia is a great post-operative problem. It may lead to serious consequences for the patient, such as injury, increased pain, hemorrhage, self-extubation, and removal of catheters, and it can necessitate physically or chemically restraining the patient. It has been reported that the incidence of postoperative emergence excitement in adults after general anesthesia is 21.3% occurrence.

Many things are mentioned as risk factors for emergence excitement. Among them, excitement after orthognathic surgery (two-jaw) was more common than after other types of surgery. The patients undergoing emergence with nasotracheal intubation after orthognathic surgery may have a sense of suffocation during emergence from anesthesia, which may increase the incidence of emergence excitement.

Pain is also a main cause of postoperative excitement. Dexmedetomidine, which is an S-enantiomer of medetomidine with high specificity for α2-adrenoceptor (α2 : α1, 1620 : 1) compared to clonidine (a2 : a1, 220 : 1), is approved as a sedative and co-analgesic drug.

To the best of the investigators knowledge, effect of dexmedetomidine on emergence excitement was investigated only in children.

The investigators hypothesized that single dose of dexmedetomidine would reduce the incidence and the severity of the emergence excitement in adults with nasotracheal intubation after orthognathic surgery (two-jaw).

Inclusion Criteria:

• ASA physical status 1 or 2 patients
• patients scheduled for orthognathic surgery (two-jaw)

Exclusion Criteria:

• severe cardiovascular disease
• allergy to dexmedetomidine
• psychological disease
• patients who cannot understand Korean