Intravenous thiobarbiturate anesthesia for cesarean section.

Abstract

A strictly controlled thiobarbiturate–succinylcholine–oxygen sequence, with thiobarbiturate dosage 4-7 mg/kg, seems safe for elective cesarean section. Two hundred and forty-eight patients were divided into four groups, which received 4, 5⅓ 6⅓ or 8 mg/kg of thiobarbiturate, respectively. Blood samples for barbiturate analysis were drawn at birth from the maternal antecubital vein and the umbilical artery and vein. Apgar scores were good (7-0) in 75-90 per cent, and fair (4-6) in 6-19 per cent, of infants in the first three groups, but only 60 per cent good, 34 per cent fair, after 8 mg/kg. Amniotic or other fluid had accumulated in the oropharynxes of most infants with low scores. Factors combining to protect the fetal brain against massive invasion by thiobarbiturale from the mother include: swift decline of drug concentrations in maternal blood; nomhomogeneity of blood in the intervillous space; absence of a maternalfetal capillary bed; hepatic extraction of drug from umbilical venous blood; progressive dilution; extensive shunting in the fetal circulation.