Intravenous Bolus of Phenylephrine vs. Norepinephrine in Preventing Hypotension After Spinal Anesthesia
Condition: Anesthesia, Spinal and Epidural; Adverse Effect; Hypotension; Complications, Cesarean Section
MeSH terms: Hypotension
Study type: Interventional
Phase: Phase 4

Summary: 
      The purpose of the study is to determine if an intravenous bolus of phenylephrine is more
      effective compared to an intravenous bolus of norepinephrine associated with crystalloid
      loading for maintaining blood pressure during a spinal anesthetic for a cesarean delivery.
      Prevention of low blood pressure has been shown to decrease nausea and vomiting during and
      after cesarean delivery under spinal anesthesia. For elective cesarean delivery, all
      participants will receive spinal anesthesia with a local anesthetic and sufentanil. This
      study plans to enroll 120 pregnant women. Patients will be randomly assigned according to a
      computer generated system to be in one of two groups.
    

Detailed description: 
      This study will be a prospective, randomized, active treatment controlled trial.

      After written and informed consent are obtained, the study participants are randomly assigned
      using a computer generated table to 1 of 2 treatment groups prior to cesarean delivery.

      Group A will consist of: An intravenous bolus of 0,2 mcg/Kg of norepinephrine to maintain
      systolic blood pressure (SBP) within 80-120% of baseline before the spinal.

      Group B will consist of: An intravenous bolus of 100mcg of phenylephrine to maintain systolic
      blood pressure (SBP) within 80-120% of baseline before the spinal.

      Patients will be admitted to holding area. Baseline arterial blood pressure and heart rate
      will be measured in supine position, with left uterine displacement. Baseline blood pressure
      will be calculated by taking the mean of three consecutive SBP measurements taken 5 minutes
      apart. 500 mL of Lactated Ringers solution will be administered immediately after induction
      of spinal anesthesia at the outflow rate of 100ml per hour.

      The primary endpoint is the number of provider interventions needed to maintain the SBP
      within 100-120% of baseline for both groups. The secondary endpoint is nausea measured with
      each provider intervention after induction of spinal anesthesia, and immediately following
      delivery with 11 point verbal rating scale (0 = no nausea, 1 = nausea). Vomiting will be
      recorded whenever present during the surgical procedure.

      Bradycardia (HR less than 50 BPM) will be treated with Atropine 0.4mg IV or ephedrine 3 mg -
      12 mg IV bolus.

      Study participants will receive a standard spinal anesthetic consisting of 0.5% hyperbaric
      bupivacaine (2 mL) plus sufentanil (5 mcg) at L3-4 or L4-5. Prior to surgical incision, the
      spinal sensory level will be tested to the bilateral T6-T4 dermatomal level. The patients
      will be positioned supine with a wedge placed under the right hip to avoid aortocaval
      compression. Both the patient and the researcher's assistant (who will collect data) will be
      blinded as to the administered Phenylephrine or norepinephrine bolus. The study will end when
      cesarean section is completed and the patient transferred to the post-operative care unit.

      Measured variables will include systolic, diastolic and mean non-invasive blood pressure, the
      number and type of interventions for control of blood pressure, heart rate, incidence of
      nausea and vomiting (NV), incidence of arrhythmia and fetal cord blood analysis (pH) at
      delivery.
    

Intervention name(s): Phenylephrine; Norepinephrine
Intervention type(s): Drug; Drug
Intervention description(s): A bolus of 100 mcg; A bolus of 0,2 mcg/kg
Other intervention name(s): Noraline; Noradrénaline
Intervention MeSH terms: Phenylephrine; Oxymetazoline; Norepinephrine
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Triple (Participant, Care Provider, Investigator)
Primary purpose: Prevention
Keywords: Spinal anesthesia; cesarean; blood pressure; Norepinephrine; Phenylephrine