Effects of nitroglycerin and indomethacin on fetal-maternal circulation and on fetal cerebral blood flow and metabolism in sheep

OBJECTIVE: Our purpose was to evaluate the effects of maternal administration of nitroglycerin and indomethacin on maternal and fetal hemodynamics and on fetal cerebral blood flow and metabolism in sheep. STUDY DESIGN: Invasive vascular and fetal carotid flow monitoring was established in 12 gravid ewes. Isotonic sodium chloride solution, nitroglycerin, and indomethacin were infused maternally, and maternal and fetal heart rate, blood pressure, blood gas values, fetal carotid blood flow, and flow variability were measured. Fetal cerebral uptake of oxygen, glucose, and lactate were calculated. RESULTS: Nitroglycerin infusion caused a significant increase in maternal and fetal heart rate and a significant decrease in maternal and fetal mean arterial pressure at a dosage of 10 mu g/kg per minute, without a change in blood gas values. Neither drug had any effect on fetal carotid blood flow, flow variability, or cerebral substrate metabolism. CONCLUSION: Maternal administration of nitroglycerin and indomethacin caused no adverse maternal or fetal circulatory changes and did not alter fetal carotid blood flow or substrate metabolism.