Intravenous propofol during cesarean section: placental transfer, concentrations in breast milk, and neonatal effects. A preliminary study.

Placental transfer and neonatal effects of propofol were investigated in 21 women undergoing elective cesarean section under general anesthesia. This study was conducted in two separate phases according to the use of propofol. In both phases, anesthesia was induced with an iv bolus of 2.5 mg/kg of propofol. In phase 1 (n = 10), anesthesia was maintained with 50% nitrous oxide in oxygen and halothane. In phase 2 (n = 11), a continuous infusion of propofol at a rate of 5 mg.kg-1.h-1 was started after the induction dose. Maternal venous and umbilical cord arterial and venous samples were obtained at delivery. The propofol concentration in whole blood was measured with a high performance liquid chromatography method. Where possible, breast milk/colostrum was expressed for both phases postoperatively and a sample of blood was collected during phase 2 from neonates via a heel prick 2 h after birth. Propofol crossed the placenta, as demonstrated by concentrations found in umbilical venous blood in phase 1 (0.13-0.75 micrograms/ml) and in phase 2 (0.78-1.37 micrograms/ml). At delivery, the ratio of the drug concentration in umbilical venous blood to that in maternal blood was 0.70 +/- 0.06 for phase 1 and 0.76 +/- 0.10 for phase 2. The ratio of propofol concentration in the umbilical artery to that in the umbilical vein was 1.09 +/- 0.04 for phase 1 and 0.70 +/- 0.05 for phase 2.(ABSTRACT TRUNCATED AT 250 WORDS)