Dexamethasone and Ketamine on Change of Postoperative Mood

After receiving by IRB approval and obtaining informed consent from patients, 93 patients who are aged between 18 and 70 years old and classified as American Society of Anesthesiologists (ASA) classes I and II. Afterward, the patients will be randomly (sealed envelopes) allocated into one of three treatment; Group K (n = 31) will receive a single dose of ketamine 0.5 mg/kg i.v. plus 2 ml normal saline, Group D (n = 31) receive dexamethasone 0.5 mg/kg i.v. and a maximum dose of 8 mg plus 2 ml saline, and Group KD (n = 31) receive ketamine 0.5 mg/kg i.v. and dexamethasone 0.5 mg/kg i.v. at 5 minutes after the induction of anesthesia in a double-blinded method.