Two Norepinephrine Rescue Bolus Doses for Management of Severe Post-spinal Hypotension During Elective Cesarean Delivery
Condition: Postspinal Hypotension; Cesarean Delivery; Norepinephrine
MeSH terms: Hypotension
Study type: Interventional
Phase: Phase 4

Summary: 
      Maternal hypotension after spinal block is a common complication after subarachnoid block in
      this population whose incidence reached 60% in many reports. Hypotension is associated with
      maternal and neonatal complications; therefore, it is highly recommended to use vasopressors,
      prophylactically and interactively, for prompt control maternal blood pressure. Despite the
      presence of various preventive regimens (fluid loading, maternal positioning, and
      vasopressors), many mothers develop intraoperative episodes of hypotension which requires the
      use of a vasopressor bolus.

      Norepinephrine (NE) is an alpha adrenergic agonist with weak beta adrenergic agonistic
      activity; and is increasingly used in obstetric anesthesia with acceptable maternal and
      neonatal outcomes. NE bolus could be used for rapid correction of maternal blood pressure in
      a dose which variedranged between 3.7-10 mcg. Till date, al the available data for the
      management of maternal hypotension did not differentiate between severe and non-severe
      hypotension. The incidence of severe maternal hypotension (systolic blood pressure ≤60% of
      baseline) ranged between 7-20%. In a recent report, Hassabelnaby et al compared 6 mcg and 10
      mcg NE boluses in management of maternal hypotension and found that the doses had the same
      success rate (≈90%); however, most of the participants in the mentioned study had non-severe
      hypotension. Therefore, we hypothesize that severe hypotension should be separately
      investigated for the possible superiority of the higher over the lower dose of NE bolus.

      Insufficient NE bolus would lead to failed management and prolonged hypotensive episode,
      whereas a higher dose might lead to reactive hypertension and/or bradycardia, which is
      sometimes severe. Therefore, determining the optimum dose for NE bolus would enable proper
      control of maternal hemodynamic profile
    

Detailed description: 
      Upon arrival to the operating room, the patient will be in supine position with left uterine
      displacement using a wedge below the right buttock. Routine monitoring will be applied
      (electrocardiography, pulse oximetry, and non-invasive blood pressure monitor). An
      18G-cannula will be inserted, and the patients will receive 10 mg metoclopramide. Baseline
      heart rate and systolic blood pressure will be recorded as the average of three consecutive
      readings with 2-minutes interval.

      Lactated Ringer's solution will be infused at rate of 15 mL/Kg over 10 minutes as a co-load;
      spinal anesthesia will be achieved by injecting 10 mg of hyperbaric bupivacaine and 20 mcg
      fentanyl into the subarachnoid space at L3-L4 or L4-L5 interspace using 25G spinal needle.

      After subarachnoid block, mothers will be placed in the supine position with left-lateral
      tilt. The decision to give prophylactic vasopressor infusion will be according to the
      attending anesthetist preferences.

      Block success will be assessed after 5 minutes from intrathecal injection of local
      anesthetic; and will be confirmed if sensory block level is at T4.

      The patient would receive the study drug only if she developed severe post-spinal hypotension
      (defined as systolic blood pressure ≤60% of the baseline reading) as her first hypotensive
      episode or after 10 minutes from the last successfully managed hypotensive episode and before
      the delivery. .

      The management of the hypotensive episode will be considered successful if the systolic blood
      pressure is > 80% of the baseline within 2 mins of the bolus. If the bolus failed, NE bolus
      of 5 mcg will be given.

      Any other hypotensive episode (systolic blood pressure <80% of baseline) will be managed with
      NE bolus of 5 mcg.

      Intraoperative bradycardia (defined as heart rate less than 55 bpm) will be managed by IV
      atropine bolus (0.5 mg) will be administered.

      Fluid administration will be continued up to a maximum of 1.5 liters. An oxytocin bolus (0.5
      IU) will be delivered over five seconds after delivery then infused at a rate of 2.5 IU/hour.
    

Intervention name(s): Norepinephrine 5 mcg; Norepinephrine 10 mcg
Intervention type(s): Drug; Drug
Intervention description(s): norepinephrine bolus of 5 mcg for treatment of sever postspinal hypotension; norepinephrine bolus of 10 mcg for treatment of sever postspinal hypotension
Intervention MeSH terms: Norepinephrine
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
Primary purpose: Treatment