The investigator will examine the effects of opioid free anesthesia in patients undergoing
laparoscopic gastrectomy. The investigator expect that opioid free anesthesia will reduce
postoperative pain and opioid consumption.
And investigator will analyze the association between postoperative pain and patient's
underlying psychological characteristics and pain sensitivity. The investigator anticipate
that psychological characteristics and pain sensitivity may be realted to postoperative pain
and opioid consumption.