Effects of opioid-free anaesthesia compared with balanced general anaesthesia on nausea and vomiting after video-assisted thoracoscopic surgery: a single-centre randomised controll... oleh Yu Guo, Tong Wang, Jie Huang, Jia-Feng Wang, Rui Bao, Wei-shi Zhang, Yi-feng Zha, Zhen-zhen Zhao, Jia-lin Li, Jin-jun Bian