To study the effect of different doses of sufentanil on anesthesia induction and analgesia after tonsillectomy in children. According to the different doses of sufentanil used in anesthesia induction, the children were divided into 3groups. The vital signs during anesthesia, the recovery period of anesthesia and the complications after anesthesia were compared among the groups. The anesthetic effects and safety of sufentanil at different doses were discussed, which provided theoretical basis for clinical selection of the best drug dosage.

Fifteen minutes before operation, midazolam 0.1 mg/kg was slowly intravenously injected. Five minutes later, the child entered the operating room. Pi, Narcotrend, blood pressure, ECG, SpO2 and body temperature were monitored. Penehyclidine hydrochloride 0.01 mg/kg, dexamethasone 0.1 mg/kg, propofol 3 mg/kg, sufentanil (0.3μg/kg, 0.4 μg/kg, 0.5 μg/kg) were given during anesthesia induction. cis-atracurium 0.15 mg/kg, using the required type of tube for tracheal intubation. Sevoflurane 1.0 MAC + remifentanil 0.15 ug/kg/min 50% oxygen was given during anesthesia maintenance. Effective analgesia was achieved by adjusting the dosage of remifentanil during operation.

The changes of vital signs including perfusion index, Narcotrend, Bp, HR, oxygen saturation were observed before anesthesia induction, immediately after tracheal intubation, during tonsillectomy and adenoidectomy during operation, after extubation and in the recovery room. Then record the recovery time, restlessness and pain score during recovery period, postoperative pain, nausea and vomiting and other complications.

Inclusion Criteria:

• Age 1-12 years,
• ASA I-II grade;
• selective adenotonsillectomy
• BMI 18.5～23.9,
• Sign informed consent

Exclusion Criteria:

• Emergency surgery;
• Abnormal liver and kidney function
• severe dehydration and malnutrition or Hb < 10g/dl;
• BMI <18.5 or <23.9;
• Children with neurological disorders

According to the results of the experiment and the opinions of the children's families, it is decided whether to publish the data or not.

Observers and patients were double-blind. Sufentanil was assigned by a specialist. Different doses of sufentanil were allocated in the same volume according to the weight of the child.