Pre-anesthetic use of butorphanol for the prevention of emergence agitation in thoracic surgery: A multicenter, randomized controlled trial oleh Tao Meng, Xiaowen Lin, Ximing Li, Fangli Yue, Yuzhu Zhang, Yingbin Wang, Jianhua Gu, Zaiqi Yang, Hongli Yu, Kun Lv, Shengyong Liang, Xingda Li, Weibo Zhu, Gang Yu, Tao Li, Yujia Ren, Yandong Li, Jianjun Xu, Weimin Xu, Shu Wang, Jianbo Wu, Jianbo Wu