20 min before anesthesia induction , bilateral Neiguan ( PC 6 ) , Neimadian , Hegu ( LI 4 ) , Yangxi ( LI 5 ) , Zhongji ( CV 3 ) , Qichong ( ST 30 ) , Zuwuli ( LR 10 ) were selected and punctured in the treatment group , and elecctroacupuncture was given after arrival of qi until 30 min after the wake-up from anesthesia and withdrawal of endotracheal tube .