Study intervention and determination of the ED50 of esketamine
Group E received different doses of esketamine (Jiangsu Hengrui Medicine Co., Ltd.) through intravenous administration before the skin incision. The patients in group C received the same quantity of saline at the same time. The EC50 and ED95 of esketamine for the patient were determined by the up-down allocation methodology [The starting dose of esketamine was set at 0.3 mg/kg for the first participant, as determined by drug instructions. This dose is commonly used in clinical practice and many studies [
Dixon and Massey up-and-down plot line chart. The sequence of patients receiving esketamine in Group E. The quality of analgesia was measured using VAS (from 0 to 10) and was defined as ineffective (VAS score ≥ 3) or effective (VAS score<3)