Children undergoing general anesthesia for surgery commonly need sedative and anxiolytic premedication but little clinical evidence supports is benefit for children older than 7 years old.

The aim of this prospective randomized clinical trial is to assess the impact of pharmacologic premedication on perioperative children experience.

Surgery is a stressful experience in children with preoperative and postoperative anxiety.

For preschooler undergoing surgery, anxiety is the highest in the preoperative period.

Most of studies have been conducted on young children (< 7yrs old) to show the relationship between preoperative anxiety and emergence of delirium and postoperative maladaptive behavioral changes.

Sedative and anxiolytic medication is frequently used in children to reduce anxiety and postoperative maladaptive experiences. Nevertheless, little clinical evidence supports is benefit for children older than 7 years.

Treating anxiety is not necessarily associated with better experience in all children because premedication causes postoperative sedation, amnesia and cognitive impairment.

The aim of this prospective randomized clinical trial is to assess the impact of pharmacologic premedication on perioperative children experience using self-report questionnaire.

Patients are randomized to 2 groups to received pharmacologic premedication or placebo.

For the premedication group, children are randomly allocated to be premedicated with either with the midazolam or dexmedetomidine

Inclusion Criteria:

• Subject over 7 and under 18 years of age
• Subjects who are scheduled for surgery
• Subject who will be under general anesthesia
• Subject able to complete a self-questionnaire in French

Exclusion Criteria:

• Subject who has already participated in the pediaPREM study
• Subject with a treated anxiety disorder
• Subject with cognitive disorders
• Subject suffering from chronic pain (outside the operated area)
• Subject with ADD (Attention Deficit Disorder) with or without hyperactivity, with or without treatment
• Subject suffering from mental retardation
• Subjects receiving psychotropic treatment
• Subject whose intervention could reduce the ability to complete a self-questionnaire (neurosurgery etc.)
• Subject with a contra-indication to midazolam and its excipients
• Subject with a contra-indication to dexmedetomidine and its excipients
• Subjects who need to receive intravenous alpha agonist in perioperative
• Subjects requiring emergency intervention
• Subjects requiring preoperative hypnosis
• Subject who needs general anesthesia for diagnostic purposes (biopsy, etc...)
• Subject having had a surgical intervention in the month preceding the inclusion.
• Subject who will have an iterative surgical intervention within 15 days (removal of material, burns etc...)
• Subjects who are scheduled for surgery as part of oncology management
• Pregnant or breastfeeding woman
• Subject whose two parents have not signed a written informed consent
• Subjects who are not affiliated with or benefiting from a social security plan

Physicians, the nurse responsible for administration, the staff following the patient and the patient will be blinded to randomisation.

Only the nurse involved in the preparation of experimental treatments is not blinded. She will not be involved in the follow-up of the study.