The Influence of Perioperative Administration of Dexmedetomidine on Inflammation Response and Postoperative Recovery in Patients Undergoing Robot or Laparoscopic Assisted Gastrectomy

Inclusion Criteria: * 1\. 20-70 yrs old patients * 2\. Scheduled for robot or laparoscopic gastrectomy * 3\. Body weight under 90kg and BMI under 32 Exclusion Criteria: * 1\. Emergency operation * 2\. Reoperation * 3\. Co-operation with other surgery department * 4\. Co-operation with other organs (except cholecystectomy) * 5\. Patients with history of heart failure (unstable angina, congestive heart failure) * 6\. Patients with history of arrhythmia (specially AV nodal block), ventricular conduction problem * 7\. Patients with history of uncontrolled hypertension (diastolic BP \>110mmHg), extremely bradycardia (HR \<45 bpm on ECG) * 8\. Patients with history of cerebrovascular disease (cerebral hemorrhage, cerebral ischemia * 9\. Patients who is steroid user * 10\. Patients who is beta blocker user * 11\. Patients with history of liver failure, renal failure, allergic to medicine * 12\. Patients with history of uncontrolled psychiatric disease (PTSD, anxiety, depression) * 13\. Patients who cannot read the consent form (examples: Illiterate, foreigner) * 14\. Patients who withdraw the consent