The EC90 of remifentanil for inhibiting endotracheal intubation responses under anesthesia induction with ciprofol: study protocol for a dose-finding trial with the biased-coin design - Jianing Guo; Fangsheng Xu; Luoyun Li; Zeru Zhang; Baichun Xing; Qin Fan; Zehua Wang; Chunyu Li (Trials, 2024)