Comparison of Two Doses of Norepinephrine in Preventing Hypotension After Spinal Anesthesia
Condition: Anesthesia; Adverse Effect; Hypotension; Cesarean Section Complications; Vasopressor
MeSH terms: Hypotension
Study type: Interventional
Phase: Phase 4

Summary: 
      The purpose of the study is to determine the more effective intravenous bolus of
      norepinephrine for maintaining blood pressure during a spinal anesthesia for a cesarean
      delivery with the fewer side effects. Low blood pressure has been shown to decrease uterine
      perfusion and foetal outcomes during cesarean delivery under spinal anesthesia. For elective
      or semi-urgent cesarean delivery, all participants will receive spinal anesthesia with a
      local anesthetic and either sufentanil or fentanyl. This study plans to enroll 124 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, the study participants will be randomly assigned using a
      computer generated table to 1 of 2 treatment groups prior to cesarean delivery.

      Group A will receive an intravenous bolus of 1mcg/Kg of norepinephrine bitartrate to maintain
      systolic blood pressure (SBP) within 80-120% of baseline before the spinal anesthesia.

      Group B will receive an intravenous bolus of 0.5mcg/kg of norepinephrine bitartrate to
      maintain systolic blood pressure (SBP) within 80-120% of baseline before the spinal
      anesthesia.

      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 as the mean of three consecutive SBP measurements taken 3 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 endpoints are:

      the timing of the first maternal hypotension before delivery (defined as a decrease of SBP
      >20% of baseline and/or PAS<100mmHg) the delta PAS and delta PAM before delivery ( difference
      between basline and the lowest systolic and mean blood pressure respectively)

      The secondary endpoints are:

      Incidence of hypotension,norepinephrine consumption (mean dose of Norepinephrine to maintain
      blood pressure between 80 and 100 % of baseline values after the primary preventive bolus),
      nausea and vomiting will be recorded whenever present during the surgical procedure as well
      as reactive hypertension (defined as a rise of SBP >20% of baseline or SBP>140mmHg) and
      arrhythmia. Bradycardia (HR less than 50 BPM) will be treated with Atropine 0.5mg IV. Fetal
      cord blood analysis will be done immediately after delivery in order to determine the pH
      value ( ie : logarithm of the blood concentration of hydrogen ions H+)in each group

      Study participants will receive a standard spinal anesthetic consisting of 0.5% hyperbaric
      bupivacaine (2 mL) with either sufentanil (5 mcg) or fentanyl (50 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 Norepinephrine bolus A or B.

      When PAS<80% of baseline or < 100 mmHg a bolus of Norepinephrine will be administrated(half
      dose A or B).

      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,
      heart rate, number of rescue boluses , incidence of nausea and vomiting (NV), incidence of
      arrhythmia, Apgar score and fetal cord blood analysis (pH) at delivery.
    

Intervention name(s): Norepinephrine: 1mcg/kg; Norepinephrine 0,5mcg/kg
Intervention type(s): Drug; Drug
Intervention description(s): intervention:Parturients will receive Norepinephrine: a bolus of 1 mcg/Kg immediately after SA (preventive bolus) then they will receive complementary doses of Norepinephrine (half dose: 0.5 mcg/Kg) to maintain systolic blood pressure above 80 % of baseline; intervention: Parturients will receive Norepinephrine: a bolus of 0.5 mcg/Kg immediately after SA (preventive bolus) then they will receive complementary doses of Norepinephrine (half dose: 0.25 mcg/Kg) to maintain systolic blood pressure above 80 % of baseline
Other intervention name(s): Noraline; Noradrenaline; Noraline; Noradrenaline
Intervention MeSH terms: Norepinephrine
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Triple (Participant, Care Provider, Investigator)
Primary purpose: Prevention
Keywords: spinal anesthesia; blood pressure; norepinephrine; Cesarean Section