Studies showed dexmedetomidine (DEX) could improve surgical field, but the effect for functional nasal endoscopic surgery (FESS) was unclear. The investigators explored IV administration of a single loading dose DEX (0.5μg/kg) for FESS, and IV administration of midazolam (0.05mg/kg) as a control with comparision of surgical field, haemodynamics, ventilation parameters and recovery.

The participants received an induction of anesthesia with propofol 2-3 mg/kg, sufentanyl 0.2 μg/kg, and rocuronium 0.6 mg/kg, and then insertion of a flexible laryngeal mask airway was conducted using the index finger insertion technique by anesthesia providers with a minimum of four years endotracheal intubation experience. Mechanical ventilation parameters were as follows: pressure-controlled ventilation mode, ventilation pressure: 12, respiratory rate: 12, oxygen concentration: 50%. The maintenance of general anesthesia was performed with sevoflurane at minimum alveolar concentration of 1.3. After induction, a single loading dose DEX (0.5μg/kg) was IV infusion within 10 minutes, or IV administration of midazolam (0.05mg/kg). Heart rate, blood pressure, tidal volume, ventilation pressure and ETCO2 after insertion of a LMA, 10 minutes, 20 minutes, 30 minutes after drug infusion and transferred to PACU, besides heart rate and blood pressure were recorded before and after induction. Surgical field was evaluated at the time of 10 minutes and 20 minutes after drug infusion. Blood gas analysis was performed just transferred to PACU and before transferred to ward.

Inclusion Criteria:

• 120 participants who diagnosed with nasosinusitis
• The participants need undergo functional nasal endoscopic surgery
• The participants signed the informed consent

Exclusion Criteria:

• The participants were excluded with any diseases about respiration, circulation, liver and kidney
• The participants were rejected of the consent