Dexmedetomidine can be used as a co-induction agent to facilitate laryngeal mask airway (LMA) insertion with minimal effect on respiratory function. The purpose of the study was to determine the median effective dose (ED50) of dexmedetomidine to facilitate LMA insertion during anaesthesia induction with propofol 2.0 mg/kg.

Dexmedetomidine is a highly selective α2 receptor agonist, which produces sedative, anxiolytic and analgesic effects without causing clinically significant respiratory depression. Dexmedetomidine also reduces the propofol requirement for sedation and anaesthesia induction. Therefore, dexmedetomidine may be a useful co-induction agent to facilitate LMA insertion with minimal effects on respiratory function. A recent study showed that dexmedetomidine administration prior to propofol induction provided similar conditions for successful LMA insertion, as does fentanyl without respiratory depression. The purpose of this study was to determine the median effective dose (ED50) of dexmedetomidine required for successful LMA insertion during induction with propofol of 2 mg/kg .

Inclusion Criteria:

1. ASA Ⅰ ~ Ⅱ women undergoing Laparoscopic surgery.
2. Written informed consent from the patient or the relatives of the participating patient.
3. BMI:18.5～25

Exclusion Criteria:

1. Mental illness can not match
2. epidural anesthesia contraindicated
3. People who have Slow-type arrhythmias
4. Chronic renal failure
5. Alcohol or drug abuse
6. Already taking gabapentin, pregabalin, benzodiazepin or antidepression drug