Intranasal dexmedetomidine has shown to be an effective sedative when used prior to anaesthetic induction as premedication. 1mcg/kg intranasal dexmedetomidine was used in previous study and it produced satisfactory sedation in more than 50% of the children at the time of anaesthetic induction with no adverse effect. In this study we aim to compare 1mcg/kg with 2mcg/kg intranasal dexmedetomidine in children. We expect more children would attain satisfactory sedation prior to anaesthetic induction when higher dose is used.

Inclusion Criteria:

• Age 1-12 years old
• American Society of Anesthesiologists (ASA) 1-2
• Elective surgery
• Children with autism or pervasive personality disorder

Exclusion Criteria:

• American Society of Anaesthesiologists (ASA) 3-5
• Allergy or hypersensitive reaction to dexmedetomidine
• Known cardiac arrhythmia or congenital heart disease
• Mentally disabled