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Preeclampsia | Phenylephrine in Spinal Anesthesia in Preeclamptic Patients

Preeclampsia research study

What is the primary objective of this study?

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.

Who is eligible to participate?

Inclusion Criteria: - ASA PS II - III women - 18 years old and older - scheduled for cesarean delivery (no trial of labor) - eligible for spinal anesthesia - diagnosis of preeclampsia Exclusion Criteria: - patients with failed trial of labor - preexisting hypertension - body mass index (BMI) ≥ 40 kg/m2 - resting heart rate < 60 bpm - progression to eclampsia, > twin gestation - known fetal anomalies - contraindications to spinal anesthesia - emergency procedure or refusal of consent - failure to achieve a T6 level of anesthesia - conversion to general anesthesia

Which medical condition, disease, disorder, syndrome, illness, or injury is researched?

Preeclampsia

Hypotension

Study Interventions

Interventions can include giving participants drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available or noninvasive approaches such as surveys, education, and interviews.

Drug:EphedrineEphedrine concentration: 8 mg/mL. The infusion will be initiated immediately after completion of the spinal injection at a rate of 1 mL/min and continued for a minimum of 2 min after which the infusion will be stopped, continued or increased based on the SBP each minute. After each SBP measurement the infusion will be stopped if SBP > 80% baseline, and the infusion will be continued or restarted if the SBP is approximately equal to 80% baseline. The infusion will be increased by 1 mL/min if the SBP < 80% baseline. Each time there is hypotension the patient will receive a 1 mL IV bolus of the study solution and the infusion will be increased by 1 mL/min until delivery.

Drug:PhenylephrinePhenylephrine concentration: 100 mcg/mL. The infusion will be initiated immediately after completion of the spinal injection at a rate of 1 mL/min and continued for a minimum of 2 min after which the infusion will be stopped, continued or increased based on the SBP each minute. After each SBP measurement the infusion will be stopped if SBP > 80% baseline, and the infusion will be continued or restarted if the SBP is approximately equal to 80% baseline. The infusion will be increased by 1 mL/min if the SBP < 80% baseline. Each time there is hypotension the patient will receive a 1 mL IV bolus of the study solution and the infusion will be increased by 1 mL/min until delivery.

Study Arms

Research studies and clinical trials typically have two or more research arms. An arm is a group of people who receive the same treatment in the study.

PhenylephrineSubject will receive a phenylephrine infusion to prevent and to treat hypotension associated with spinal anesthesia

EphedrineSubject will receive an ephedrine infusion to prevent and to treat hypotension associated with spinal anesthesia

Study Status

Completed

Start Date: July 2006

Completed Date: December 2016

Phase: N/A

Type: Interventional

Design:

Primary Outcome: The umbilical artery pH in the phenylephrine group will be higher than in the ephedrine group, although the overall incidence of absolute fetal acidosis is not anticipated to be different between groups.

Secondary Outcome: Efficacy of study drug in preventing and treating hypotension associated with spinal anesthesia in women with preeclampsia

Study sponsors, principal investigator, and references

Principal Investigator: Cynthia A. Wong, M.D.

Lead Sponsor: Northwestern University

Collaborator:

More information:https://clinicaltrials.gov/show/NCT00458003

Rout CC, Rocke DA. Prevention of hypotension following spinal anesthesia for cesarean section. Int Anesthesiol Clin. 1994 Spring;32(2):117-35. Review.

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