Children are prone to anxiety and even fear before surgery, and such adverse emotions may not only lead to poor induction of anesthesia, but also increase the incidence of postoperative agitation and even lead to postoperative behavioral changes in children. There are many ways to relieve pediatric anxiety, including preoperative medication, games, and cartoons. Preoperative medication is the most commonly used method to relieve pediatric anxiety.The most commonly used pediatric preoperative sedation drugs are midazolam and esketamine.However, oral midazolam may not produce a sedative effect in 20-40% of patients. A good preoperative anxiety-reducing effect was seen in only 60-80% of cases.Therefore, this trial investigates whether the intranasal combination of esketamine with oral midazolam can produce better results than each of the two drugs alone. This will provide a reference for the selection of safe, reliable and appropriate preoperative sedation methods for pediatric patients and provide evidence-based support for comfort care.

A trained member of the research team obtained a baseline The Modified Yale Preoperative Anxiety Scale(mYPAS) after obtaining consent. And corresponding study medication is administered about 30-40 minutes before the anesthesia induction.Vital signs were measured every 5 min after study medication administration.The sedation scores of the children were recorded with University of Michigan Sedation Scale (UMSS) every 10 minutes.The onset time of satisfactory sedation and parental separation anxiety scale was noted.Then recorded the degree of cooperation during inhalation anesthesia induction and recovery times.Moreover, recorded the pediatric anesthesia emergence delirium scale (PAED) during the recovery period.

Inclusion Criteria:

1. with American Society of Anesthesiologists (ASA) physical status I or II；
2. aged 2-6 years；
3. children with weight for age within the normal range
4. were scheduled lower abdominal and perineal surgery with an expected operation time shorter than 30 minutes.

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 either esketamine or midazolam;
3. with any nasal pathology,organ dysfunction;
4. recently respiratory infection, mental disorder;
5. other reasons that researchers hold it is not appropriate to participate in this trial.