Department of Otorhinolaryngology Head and Neck Surgery;
Tongji Hospital;
Tongji Medical College;
Huazhong University of Science and Technology;
Wuhan 430030;
China;
Department of Anesthesiology;
Tongji Hospital;
Tongji Medical College;
Huazhong University of Science and Technology;
Wuhan 430030;
China;
drug-induced sleep endoscopy; dexmedetomidine; butorphanol; obstructive sleep apnea;