Abstract: Objective To evaluate the effect and security of premedication with intranasal dexmedetomidine combined with ketamine in children. Methods A total of 100 children received sclerotherapy on venous malformations, aged 1-5 years, American Society of Anesthesiologists Ⅰ-Ⅱ, were enrolled in this study. Fifty children were given intranasal dexmedetomidine at 2 μg/kg in one nostril and intranasal ketamine of 1 mg/kg in the other nostril as study group, and 50 children were given only dexmedetomidine at 2 μg/kg as control group. Premedication was performed at 30 min before operation. Heart rate (HR) and percutaneous oxygen saturation (SpO₂) were recorded before premedication and 10 min(T1), 20 min(T2) and 30 min (T3) after premedication. When T3 after premedication modified observer’s assessment of alertness/sedation scale (MOAA/S) was assessed for children, sedation state. Parental separation anxiety scale (PSAS) was assessed for children emotional state. Sleep latency and wake-up time were recorded with intraoperative hypotension and bradycardia. Results The sedation assessed by the MOAA/S (≤; 3 points) in study group was significantly better than that in control group with statistical differences(P< 0.05). There was significant difference in PSAS scale between 2 groups (P< 0.05). There was no significant difference in HR and SpO₂ except for the decrease in HR at T3 of control group (P< 0.05). The sleep latency was shorter and wake-up time was longer in study group when compared with those in control group (P< 0.05). There was no obvious hypotension and bradycardia in both groups. Conclusions Intranasal dexmedetomidine combined with ketamine would be a safe and simple premedication in children, which could sedate children well.

Key words: Dexmedetomidine, Ketamine, Premedication, Children