Comparison of the maternal and neonatal effects of halothane, enflurane, and isoflurane for cesarean delivery.

The maternal and neonatal effects of 50% O2-50% N2O alone and 50% O2-50% N2O combined with 0.5% halothane, 1.0% enflurane, or 0.75% isoflurane were studied in 42 healthy parturients undergoing general anesthesia for elective primary or repeat cesarean delivery at term. All patients received thiopental and succinylcholine for induction and were intubated and ventilated with a tidal volume of 10 ml/kg at a rate of 10 breaths/min. Two of 12 (17%) patients given O2-N2O alone had recall; none who received a potent inhalation agent had any recall. Blood loss was similar in all four groups. There were no significant differences between groups in induction-to-delivery and uterine incision-to-delivery intervals, the frequency of Apgar scores less than 7 at 1 and 5 min, maternal and fetal blood-gas tensions, acid-base balance, lactate values, and early neonatal neurobehavioral scores at 2-4 h. It is concluded that analgesic concentrations of halothane, enflurane, and isoflurane can be safely added to 50% O2-50% N2O to prevent maternal awareness during general anesthesia for cesarean delivery while maintaining normal maternal and neonatal conditions.