Patients undergoing caesarean delivery under inhalation anaesthesia are at a high risk of awareness, especially in the period before delivery. The investgators assessed the effects of remifentanil on the bispectral index (BIS) in the interval before delivery.

Sixty primipara undergoing elective cesarean delivery were randomly assigned to receive remifentanil 1 μg kg-1 (R1) or 0.5 μg kg-1 (R0.5), or saline (control) over 15 s with induction of anesthesia using propofol 2 mg kg-1 and suxamethonium 1.5 mg kg-1.The investgators assessed the average value of BIS at the time period of before, induction , intubation, skin incision, peritoneum incision , uterine incision , and delivery. The investgators also determined the neonatal Apgar scores, and conducted umbilical artery blood gas analysis.

Inclusion Criteria:

• ASA physical status I or II who elected to undergo Caesarean section, under general anaesthesia

Exclusion Criteria:

• multiple fetuses,preterm delivery, known fetal anomalies, pregnancy-induced hypertension, or any other medical complication