Remimazolam has demonstrated the potential as a valuable medication for procedural sedation and general anesthesia. However, half effective dose of remimazolam required to prevent cardiovascular response to tracheal intubation when combined with fentanyl in pediatric patients is still unknown.

Inclusion Criteria:

• age from 3 to 12 years old
• patients scheduled for surgery under general anesthesia
• Body mass index in the range of 5% -95% of the same age group
• Consent was obtained from the patient and the family members, and an informed consent form was signed

Exclusion Criteria:

• American Society of Anesthesiologists status ≥3
• patients who cannot cooperate with intravenous anesthesia induction
• patients with risk of difficult airway
• patients who are allergic to benzodiazepines
• patients with neurological dysfunction
• Participate involved in other clinical investigators within 3 months