Awareness following different techniques of general anaesthesia for caesarean section

Using the isolated arm technique, the frequency of awareness was evaluated in 50 full-term patients undergoing elective Caesarean section under general anaesthesia. In 20 patients, anaesthesia was induced with thiopentone 4 mg kg-1, and in the other 30 patients, induction was with ketamine 1.5 mg kg-1. Following suxamethonium 1.5 mg kg-1 and tracheal intubation, anaesthesia was supplemented during the induction-delivery period in the thiopentone group with 50% nitrous oxide and 0.5% halothane in oxygen in 10 patients, and with 1% halothane in 100% oxygen in the other 10 patients. In the ketamine group, the patients underwent ventilation with 50% nitrous oxide and 0.5% halothane in oxygen in 10 patients, with 1% halothane in 100% in 10 patients, and with 100% oxygen only in the last 10 patients. Awareness was significantly greater after induction with thiopentone (14/20) than after ketamine (4/30). There were no significant differences in Apgar scores or umbilical vein blood-gas values in the newborns.