[Enflurane and fluorconcentrations in maternal and fetal blood during anaesthesia for for caesarean Section (authors...

During anaesthesia for caesarean sections, the placental transfer and metabolism of Enflurane were investigated in 14 cases. In 3 cases, the administered concentration of 0.4 vol.% Enflurane showed too slight anaesthesia. In 11 cases, 0.6 vol.% Enflurane were delivered to the maternal respiratory mixture. A gaschromatographic method was used to measure the maternal and fetal blood concentrations of Enflurane. The calculated maternal mean value of Enflurane showed a concentration of 330 mumol/l which corresponds to 6.07 mg/100ml; the fetal mean value was 148 mumol/l or 2.72 mg/100 ml. This means that during operating time about 44.8% from the maternal Enflurane concentration has crossed to the fetus. The metabolic break down of Enflurane could be demonstrated by the measurement of inorganic fluorides in the maternal and fetal blood. The fluor concentration in the maternal blood increased during the operation and reached a mean value of 15.5 mumol/l at the time of birth; the mean value in the cord vein was at the same time 9.28 mumol/l which corresponds to 61% of the maternal concentration.