Epinephrine Does Not Alter Human Intervillous Blood Flow during Epidural Anesthesia

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Abstract
The effect of epinephrine given epidurally with local anesthetics on uterine blood flow is controversial. Previous work in pregnant ewes demonstrated a transient but significant (14%) decrease in uterine blood flow when 2-chloroprocaine with epinephrine (10 .mu.g/ml) was used. 2-Chloroprocaine (10 ml) with epinephrine (5 .mu.g/ml) was given to 12 healthy women during the 1st stage of labor. I.v. 133Xe was used to measure intervillous blood flow before and 15-20 min after epidural anesthesia to a somatic level of at least T thoracic 10. Intervillous blood flow did not change significantly despite a decrease in mean blood pressure of 11 torr. These conflicting results are probably best explained by methodologic and species differences. Human placental vasculature, unlike that of the ewe, may undergo vasodilatation when perfusion pressure is decreased to maintain placental blood flow.