Anaesthesia was maintained with 0.5-1 MAC of isoflurane with nitrous oxide 50% in oxygen to maintain the heart rate and blood pressure within 20% of baseline values. Neuromuscular block was maintained with vecuronium 0.06 mg/kg. The lungs were ventilated using a tidal volume of 8 mL/kg, an inspiration-expiration ratio of 1: 2, and at a respiratory rate necessary to maintain an EtCO2 of 30-35 mm Hg. An infusion of lactated Ringer's solution 800 mL was given to all subjects during the procedure. Induction to delivery (I-D) times was recorded using a stopwatch.