Due to the incomplete development of systems and low pain thresholds in the pediatric population, good general anesthesia is required during the perioperative period to ensure the smooth progress of the surgery.Propofol is often used for anesthesia induction in clinical work, which can achieve good anesthesia effects. However, this drug has obvious injection pain and is prone to significant inhibition of blood circulation, and may even lead to adverse conditions such as respiratory depression in children. For the pediatric population, maintaining appropriate anesthesia depth and stable circulation during the induction period of general anesthesia has always been a focus of attention and research by anesthesiologists.Remimazolam besylate is a new type of water-soluble ultra short acting benzodiazepine drug that is hydrolyzed and metabolized by plasma esterase in the body, independent of liver and kidney function, and the metabolite zolam propionic acid has no pharmacological activity; Rapid onset and failure, short sedation recovery time; Has little impact on respiration and circulation; And there is no injection pain.Remazolam besylate is highly suitable for children due to its characteristics, and some studies have demonstrated the safety of intravenous injection of Remazolam besylate. However, there is limited research on its dosage exploration, which to some extent limits its clinical application in children.This study aims to explore the 95% effective dose (ED95) of single intravenous injection of remidazolam besylate in children of different age groups, providing a theoretical basis for the use of remidazolam besylate in pediatric anesthesia.

This experiment was divided into three groups based on the age of the children, namely 1-3 years old, 4-6 years old, 7-12 years old, with an initial dose of 0.2mg/kg. The time of consciousness loss in the children was evaluated after injection of ramazolam besylate to determine whether sedation had been achieved. The next dose was adjusted to 0.05mg/kg according to biased coin design,to further explore the ED95 of a single intravenous injection of ramazolam in children of different age groups.

Inclusion Criteria:

1. with American Society of Anesthesiologists (ASA) physical status I or II；
2. aged 1-12 years；
3. children with weight for age within the normal range；
4. were scheduled general anesthesia surgery

Exclusion Criteria:

1. Children who had gastrointestinal,Cardiovascular or endocrine dysfunction;
2. contraindication to preoperative sedation or had a known allergy or hypersensitive reaction to remimazolam;
3. recently respiratory infection, mental disorder;
4. other reasons that researchers hold it is not appropriate to participate in this trial.