2.3. Anesthesia protocol

Atropine was intramuscularly injected at 0.02 mg/kg 30 minutes before operation for all patients, followed by oxygen inhalation and intravenous induction. Remifentanil 1 μg/kg and propofol 4 mg/kg were intravenously injected 3 to 5 minutes before operation, with or without sufentanil 0.1 μg/kg or oxycodone 0.1 mg/kg. Cisatracurium (0.05 mg/kg) was injected intravenously, and tracheal intubation was conducted after assisted respiration for 3 min. Propofol 4–12 mg/kg/h and remifentanil 0.05 to 0.1 μg/kg/h were infused continuously to sustain anesthesia. Hydroxyethyl starch was injected at 10 mL/kg/h to sustain circulation stability. All operations were performed by an experienced attending otolaryngologist. Mechanical ventilation was used, and the tracheal tube was removed under vacuum during the recovery period, followed with immediate clearing of secretions and residual blood in the oropharynx. No perioperative steroids were used.

The patients were observed for 15 to 30 minutes before sufentanil at 0.6 μg/kg/d using a BCDB-100 electronic analgesia pump (Shanghai Bochuang Medical Equipment Co., Ltd, China). The drug was diluted in normal saline to 100 mL and continuously injected at 4 mL/h for 24 hours.