Abstract: Objective：To investigate the effect of low-dose esketamine on relieving pain of propofol medium-chain triglyceride/long-chain triglyceride (MCT/LCT) emulsion injection in children.Methods：A total of 165 children undergoing general anesthesia treated in Hunan Children′s Hospital from July to December 2023 were selected as the study subjects,and they were randomly divided into 3 groups:control group,esketamine group and lidocaine group,55 cases in each group.The esketamine group was injected with 0.2 mg/kg esketamine before propofol MCT/LCT injection,the lidocaine group was injected with 0.5 mg/kg lidocaine,and the control group was injected with the same volume of normal saline.The incidence of injection pain,pain score and adverse reactions were recorded.Results：The incidence of injection pain in esketamine group and lidocaine group was 20.0% (11/55) and 21.8% (12/55),which was significantly lower than that in control group (45.5%,25/55),and the difference was statistically significant(P<0.05).The pain score of esketamine group and lidocaine group was (0.22±0.46) and (0.27±0.56) respectively,which was significantly lower than that of control group(0.87±1.10),and the difference was statistically significant (P<0.05).There was no significant difference in the incidence of injection pain or pain score between esketamine group and lidocaine group(P>0.05).There was no significant difference in the incidence of adverse reactions among the three groups（P>0.05）.Conclusion：Low-dose esketamine pre-treatment can reduce the incidence and intensity of pain from propofol MCT/LCT injection in children,which is equivalent to lidocaine,and there are no serious complications.

Key words: Propofol medium-chain triglyceride/long-chain triglyceride emulsion, Injection pain, Esketamine, Lidocaine；Child