Abstract: Objective To observe the effect of intravenous small dose of ketamine combined with continuous infusion of propofol and sufentanyl in painless gastroscopy.Methods 62 patients undergoing painless gastroscopy under intravenous anesthesia were randomly divided into the control group and ketamine group with 31 cases in each group. The cases of the control group were treated with continuous infusion of propofol (target controlled infusion rate: 3.0 μg/ml) and sufentanyl (loading dose: 0.15 μg/kg, basal rate 0.15 μg/kg/h); those of the ketamine group were treated with intravenous small dose of ketamine 0.5 mg/kg combined with continuous infusion of propofol (target controlled infusion rate: 3.0 μg/ml) and sufentanyl (loading dose: 0.1 μg/kg, basal rate 0.1 μg/kg/h). The procedure of gastroscopy was started when patients were in unconsciousness and their vital signs were stable, and the infusion of medicine was stopped when the gastroscopy was finished. The systolic blood pressure (SBP) and heart rate (HR) at the time of before anesthesia, 1 minute after anesthesia, inserting the gastroscope, 10 minutes after inserting the gastroscope, and recovering from the anesthesia were recorded. The cases needing special respiratory management (SRM), displaying body movement (BM) in gastroscopy and post-operative nausea and vomiting (PONV) were recorded. The recovery time (RT) after gastroscopy was also recorded.Results No significant difference was found in SBP, HR, BM, PONV and RT between two groups ( P>0.05). Eight cases in the control group and one case in the ketamine group needed SRM before inserting the gastroscope due to transient respiratory depression ( P<0.01).Conclusion The application of intravenous small dose of ketamine combined with continuous infusion of propofol and sufentanyl in painless gastroscopy is effective and safe.

Key words: small dose, ketamine, painless gastroscopy