Comparison Between Remifentanil Target-controlled Infusion and Dexmedetomidine Bolus Administration for Smooth Emergence From General Sevoflurane Anesthesia

Fifteen minutes before the end of surgery, the first practitioner replace the syringe of remifentanil as new one; new syringe contains remifentanil in remifentanil group (Group R), and normal saline in dexmedetomidine group (Group D), respectively. There are no drug labeling in the new syringe, so the second practitioner can't know which drug was contained in the new syringe. Simultaneously, the second practitioner remifentanil concentration on monitor of TCI pump will be adjusted to 2.0 ng•ml-1. Ten minutes before the end of surgery, 10 ml of dexmedetomidine 0.5 mcg•kg-1 mixed with normal saline will be given for 5 min in Group D; in Group R, 10 ml of normal saline will be given by the first practitioner.