Halothane anaesthesia in caesarean section.

The safety and efficacy of halothane anaesthesia were investigated in 97 caesarean sections using 0.4-0.6% halothane added to a mixture of 61 N2O/3-4 1 O2. The administration of halothane was initiated before intubation and terminated immediately prior to delivery. Only one patient reported memories from the operation. The mean Apgar score 1 min after delivery (8.5) was significantly better than that (8.2) in 100 caesarean sections in which a mixture of 71 N2O/3 1 O2 was used. In 17 caesarean sections, the halothane concentrations were examined after 0.9% halothane had been given for exactly 1 min after intubation. It was found that halothane reached and passed the placenta after only 1 min. The levels in the maternal artery and umbilical vein were comparable. The levels in the maternal artery, maternal vein and umbilical vein were markedly higher than in the umbilical artery, which indicated an accumulation of halothane in the foetal tissues. However, due to the vigour of the newborn, halothane concentrations 10 min after birth were very low. The half-life of halothane in the maternal circulation was approximately 1 min with the described method of administration. Blood gas determinations, which were made in seven newborns, proved satisfactory.