Phenylephrine in Spinal Anesthesia in Preeclamptic Patients
Status:
Completed
Trial end date:
2016-12-01
Target enrollment:
Participant gender:
Summary
Hypotension remains a common clinical problem after induction of spinal anesthesia for
cesarean delivery. Maternal hypotension has been associated with considerable morbidity
(maternal nausea and vomiting and fetal/neonatal acidemia). Traditionally, ephedrine has been
the vasopressor of choice because of concerns about phenylephrine's potential adverse effect
on uterine blood flow. This practice was based on animal studies which showed that ephedrine
maintained cardiac output and uterine blood flow, while direct acting vasoconstrictors, e.g.,
phenylephrine, decreased uteroplacental perfusion. However, several recent studies have
demonstrated that phenylephrine has similar efficacy to ephedrine for preventing and treating
hypotension and may be associated with a lower incidence of fetal acidosis. All of these
studies have been performed in healthy patients undergoing elective cesarean delivery.
Preeclampsia complicates 5-6% of all pregnancies and is a significant contributor to maternal
and fetal morbidity and mortality. Many preeclamptic patients require cesarean delivery of
the infant. These patients often have uteroplacental insufficiency. Given the potential for
significant hypotension after spinal anesthesia and its effect on an already compromised
fetus, prevention of (relative) hypotension in preeclamptic patients is important. Spinal
anesthesia in preeclamptic patients has been shown to have no adverse neonatal outcomes as
compared to epidural anesthesia when hypotension is treated adequately. Due to problems
related to management of the difficult airway and coagulopathy, both of which are more common
in preeclamptic women, spinal anesthesia may be the preferred regional anesthesia technique.
Recent studies have demonstrated that preeclamptic patients may experience less hypotension
after spinal anesthesia than their healthy counterparts. To our knowledge, phenylephrine for
the treatment of spinal anesthesia-induced hypotension has not been studied in women with
preeclampsia. The aim of our study is to compare intravenous infusion regimens of
phenylephrine versus ephedrine for the treatment of spinal anesthesia induced hypotension in
preeclamptic patients undergoing cesarean delivery. The primary outcome variable is umbilical
artery pH.