Abstract
The widespread use of sodium amytal in obstetrics and in animal experimentation, where observations upon the fetuses are to be made, has necessitated a study of the placental transmission of this anesthetic. A review of the literature shows that there is general agreement that there is no danger to the fetus when the mother is anesthetized with this drug.
Our experiments were divided into 2 main groups: (1) those showing the effect upon the fetuses of anesthesia of the mother with sodium amytal, and (2) experiments showing the effect upon mothers of injections of this same anesthetic into the fetuses. In the first group, pregnant white rats were completely anesthetized with a 2% solution of sodium amytal. The anesthetic dose used was 80 mg. per kilo of body weight minus the estimated weight of the fetuses. It was found that the dose of sodium amytal calculated from the total weight of the pregnant animal proved lethal for the mother in 60% of the cases, but doses calculated from the weight of the mother minus the estimated weight of the fetuses were never lethal. In some cases, small amounts of ether were necessary to supplement the sodium amytal anesthesia. At various intervals, during the period of anesthesia of the mother, the fetuses were tested, both in utero and when removed from the uterine cavity. When stimulated with a needle, they responded as did the normal controls. We conclude, therefore, that sodium amytal does not pass the placenta from mother to fetus in large enough quantities to be detected by the gross tests employed.
In the second group of experiments, which were performed to determine the transmission of sodium amytal from fetus to mother, the fetuses or amnia were injected with the minimum amount of the drug necessary for complete anesthesia of the mother.
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