Ephedrine versus phenylephrine: prevention of hypotension during spinal block for cesarean section and effects on the fetus.
OBJECTIVE
Hypotension during spinal block for cesarean section is secondary to the sympathetic blockade and aorto-caval compression by the uterus and it can be deleterious to both the fetus and the mother. Ephedrine and phenylephrine improve venous return after sympathetic blockade during the spinal block. The objective of this study was to compare the efficacy of ephedrine and phenylephrine in the prevention and treatment of maternal hypotension during spinal block and to evaluate their side effects and fetal changes.


METHODS
Sixty patients undergoing spinal block with bupivacaine and sufentanil for cesarean section were randomly divided in two groups to receive prophylactic ephedrine (Group E, n = 30, dose = 10 mg) or phenylephrine (Group P, n = 30, dose = 80 microg). Hypotension (blood pressure equal or lower than 80% of baseline values) was treated with bolus administration of the vasoconstrictor at 50% of the initial dose. The incidence of hypotension, reactive hypertension, bradycardia, and vomiting, and Apgar scores on the 1st and 5th minutes, and blood gases of the umbilical cord blood were evaluated.


RESULTS
The mean dose of ephedrine used was 14.8 +/- 3.8 mg and of phenylephrine was 186.7 +/- 52.9 microg. Demographic parameters and the incidence of vomiting, bradycardia, and reactive hypertension were similar in both groups. Hypotension had an incidence of 70% in Group E and 93% in Group P (p < 0.05). The mean arterial pH of the umbilical cord blood and the Apgar score in the 1st minute were lower in Group E (p < 0.05). Differences in the Apgar score in the 5th minute were not observed.


CONCLUSIONS
Ephedrine was more effective than phenylephrine in the prevention of hypotension. Both drugs had similar incidence of side effects. Fetal repercussions were less frequent with phenylephrine and were transitory with the use of ephedrine.
CET/SBA do Centro de Anestesiologia do Hospital Universitário de Brasilia, Universidade de Brasilia (UnB), Brasilia, DF. ednomag@gmail.com
Edno
E
Magalhães
Catia Sousa
CS
Govêia
Luís Cláudio
LC
de Araújo Ladeira
Bruno Góis
BG
Nascimento
Sérgio Murilo Cavalcante
SM
Kluthcouski
D000328:Adult; D000773:Anesthesia, Obstetrical; D000775:Anesthesia, Spinal; D002585:Cesarean Section; D004311:Double-Blind Method; D004809:Ephedrine / Q000494:pharmacology* / Q000627:therapeutic use*; D005260:Female; D005333:Fetus / Q000187:drug effects*; D006801:Humans; D007022:Hypotension / Q000517:prevention & control*; D010656:Phenylephrine / Q000494:pharmacology* / Q000627:therapeutic use*; D011247:Pregnancy; D011446:Prospective Studies; D014662:Vasoconstrictor Agents / Q000494:pharmacology* / Q000627:therapeutic use*
D014662:Vasoconstrictor Agents; D010656:Phenylephrine; D004809:Ephedrine