Abstract:Objective To observe the effect of low-dose esmketamine on intravenous anesthesia with propofol and remifentanil during painless gastroenteroscopy, and to judge the feasibility of reducing respiratory depression. Methods From March to June 2021, 100 patients with painless gastroenteroscopy in Nanjing Jiangbei Hospital Affiliated to Nantong University, male or female, 20~65 years old, BMI<30, ASA grade Ⅰ~Ⅱ, were selected. They were randomly divided into two groups: esmketamine group (intravenous administration of esketamine 0.1 mg/kg for pretreatment, followed by a mixture of propofol and remifentanil) and control group (intravenous administration of sodium chloride solution 0.1 mg/kg for pretreatment, followed by a mixture of propofol and remifentanil), with 50 cases in each group. The respiratory depression, preoperative and intraoperative systolic blood pressure and heart rate, the induced dose of propofol and remifentanil mixture, the incidence of choking cough at first insertion of endoscopy, the time of awakening and staying in the anesthesia recovery room, and the incidence of postoperative adverse reactions were observed and recorded. Results Compared with the control group, the degree of respiratory depression was lower (P<0.05), the induced dose of propofol and remifentanil mixture (the first dose) and the total dosage of that mixture during operation were less(P<0.01), and the severity of postoperative intestinal spastic pain was decreased in esmolamine group (P<0.05). However, there was no significant difference in the incidence of choking cough at the first insertion of endoscopy, recovery time and adverse reactions between the two groups （P>0.05). Conclusion Low-dose esmketamine can reduce the dosage of propofol and remifentanil during painless gastroenteroscopy, reduce the severity of respiratory depression caused by remifentanil, reduce postoperative pain, and can't increase the incidence of postoperative adverse reactions.