Objective:To evaluate the effect and security of intranasal dexmedetomidine combined with ketamine on preoperative sedation in children.Methods:From 1 March to 30 June

2016

115 children of ASA I-Ⅱ

aged 2 to 6 years

scheduled to undergo uvulopalatopharyngoplasty and tonsillectomy

were randomly assigned to four equal groups.Group D1（n =37） and Group D2（n =40）received intranasal dexmedetomidine of 1 μg/kg or 2 μg/kg

respectively.Group D1 +K（n =38） and Group D2 +K（n =40） received dexmedetomidine of 1 μg/kg or 2 μg/kg in one nostril

and intranasal ketamine of 1 mg/kg in the other nostril

respectively.Children were transferred to the operating room 40 minutes later

and received general anaesthesia;after surgery they were sent to the post anesthesia care unit（PACU）.The mean arterial pressure

oxygen saturation and heart rate of patients were recorded every 15 minutes after intranasal administration.Sedation score（modified observer’s assessment of alertness/sedation score

m OAAS）was recorded at 2 time points:transferred to the operating room（T1）

and received anesthesia induction（T2）.Onset time

duration of anesthesia

duration of surgery

recovery time

pediatric anesthesia emergence delirium scale（PEAD）

postoperative pain score（face

legs

activity

crying

consolability scale

FLACC）and adverse reactions were also recorded.Results:There was no differences in demographic characteristics

duration of anesthesia

and duration of surgery between 4 groups.The onset time of sedation was significantly shorter in group D2+K than that in group D1

D2 and D1+K（P<0.05）.In T1 and T2

the success rate of sedation improved significantly in group D2+K than in group D1

D2 and D1+K（P<0.01）.The incidence of brachycardia was significantly higher in Group D2 compared with that in other 3 groups（P<0.05）.There was no statistical difference in the recovery time

PEAD and postoperative pain score between 4 groups.Conclusion:Intranasal dexmedetomidine combined with ketamine realizes better sedation and shorter onset time

thus it is a safe

effective and convenient premedication in children.