Objective: To explore the effect of etomidate and esketamine on postoperative pain after tonsillectomy in children.

Methods: Investigators enrolled 64 children with American Society of Anesthesiologists (ASA) physical status I and II, aged 2-10 years, and scheduled for elective undergoing tonsillectomy with general anesthesia. All the enrolled patients were randomly divided into etomidate and fentanyl group (Group A) and etomidate and esketamine group (Group B). In the etomidate-fentanyl group (group A), 0.3 mg/kg etomidate and 4 µg/kg fentanyl were given at the induction of anesthesia, followed by continuous infusion of propofol at 4-12 mg/kg/h and remifentanil at 3-6 µg/kg/h until the end of the surgery, respectively; in the etomidate-esketamine group (group B), induction of anesthesia with 0.3 mg/kg etomidate and 0.5 mg/kg esketamine , followed by continuous infusion of propofol at 4-12 mg/kg/h and remifentanil at 3-6 µg/kg/h until the end of the operation. Anesthesiologists who were unaware of the grouping recorded the FlACC Pain Scale at 2 h, 8 h, and 24 h after surgery.

Inclusion Criteria:

• Children who underwent elective tonsillectomy
• Aged 2-10 years old
• ASA class I-II

Exclusion Criteria:

• Children with hepatic or renal dysfunction
• Those with increased intracranial or intra-ocular pressure
• Children with schizophrenia, bipolar disorder, and any other psychiatric condition
• Children with preexisting chronic pain
• Children with preoperative combined sinus bradycardia or atrioventricular block