Results
PONV, postoperative pain, Postoperative Nausea and Vomiting, Postoperative adverse
HEART
Of the 66 laparoscopic cholecystectomy patients who were screened for inclusion, 8 met exclusion criteria, 4 refused to participate, and 54 met the inclusion criteria and were randomized into two groups of 27 patients each (Fig. 
Flow diagram
Demographic data and intraoperative outcomesNotes: ASA, American Society of Anesthesiologists; BMI, body mass index; Propofol doses, intraoperative maintenance doses. Data are expressed as number, the mean ± standard deviation or medians (quartiles). Measurement data is treated with the t-test, or Mann-Whithey U test, enumeration data is treated with the chi-square testThe sequence of effective and ineffective determined by Dixon’s up-and-down method is shown in Fig. 
Dose-response curve of esketamine for preventing early postoperative pain in patients undergoing laparoscopic cholecystectomyThe mean arterial pressure (MAP) and heart rate (HR) are shown in Table 
The intraoperative haemodynamics conditionNotes: Data are expressed as mean (standard deviation) or median (interquartile range). T
Heart rate (HR) and mean arterial pressure (MAP) at different time points during surgery. Data are expressed as mean (standard deviation) or median (interquartile range). TThe conditions of patients during anesthesia recovery are listed in Table 
The condition of patients during anesthesia recoveryNotes: VAS, Visual Analogue Scale/Score. Data are expressed as number, the mean ± standard deviation or medians (quartiles). Measurement data is treated with the t-test, or Mann-Whithey U test, enumeration data is treated with the chi-square test. * Postoperative adverse events as one of the outcomes are listed in Table 
The condition of post-operative adverse reactionsNotes: PONV, Postoperative Nausea and Vomiting. Data are expressed as number (percentage). Enumeration data is treated with the chi-square test