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 administrati on 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 estab lished in 12 gravid ewes. Isotonic sodium chloride solution, nitroglycerin, and indomethacin were infused maternally, and maternal and fetal heart rat e, blood pressure, blood gas values, fetal carotid blood flow, and flow var iability were measured. Fetal cerebral uptake of oxygen, glucose, and lacta te were calculated. RESULTS: Nitroglycerin infusion caused a significant increase in maternal a nd fetal heart rate and a significant decrease in maternal and fetal mean a rterial 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 cause d no adverse maternal or fetal circulatory changes and did not alter fetal carotid blood flow or substrate metabolism.