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摘要

Background: Phenylephrine is frequently used for the prevention and treatment of maternal hypotension in patients undergoing Cesarean section. But there are limited studies about the prophylactic effect on maternal hypotension with a loading dose, followed by a continuous infusion of phenylephrine. Therefore, we investigated the additional effect of a loading dose infusion of phenylephrine on the prevention of maternal hypotension, and compared it to a continuous infusion of phenylephrine without a loading dose. Methods: Following spinal anesthesia, sixty-four patients were randomly assigned to one of two groups according to the phenylephrine administration regimen: group L (n = 32; loading dose [200 μg/min] just before continuous infusion [20 μg/min]) and group C (n = 32; continuous infusion [20 μg/min] without a loading dose). We measured the blood pressure and heart rate, and assessed the incidence of hypotension, nausea, vomiting, dosage of used rescue drugs and fetal parameters. Results: At 2, 4 minutes after administration of phenylephrine, group L showed a higher systolic blood pressure and lower heart rate than group C. However, there were no significant differences in the incidence of hypotension, nausea, vomiting and the dosage of used rescue drugs. There were no significant differences in the fetal parameters such as Apgar scores and umbilical pH. Conclusions: The loading dose infusion of phenylephrine had no beneficial positive effect on the prevention of maternal hypotension.