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As discussed in other chapters, neuraxial anesthesia is the most common and preferred anesthetic for cesarean delivery. Induction of spinal anesthesia causes a sympathectomy leading to vasodilation and, rarely bradycardia, resulting in maternal hypotension.1 Avoiding hypotension in parturients is important as the human placenta has minimal autoregulation, and fetal perfusion is determined solely by maternal perfusion pressure. Although serious adverse events resulting from hypotension are uncommon, hypotension following spinal anesthesia induction is associated with maternal nausea and vomiting, with fetal heart rate (HR) changes, and prolonged hypotension can lead to fetal acidosis.2

Coloading with crystalloids and use of vasoconstrictive agents have been shown to lower the incidence of hypotension following administration of spinal anesthesia.3 Phenylephrine and ephedrine are most commonly used to prevent and treat spinal hypotension, largely because they are best supported by existing evidence.2,4,5 Phenylephrine is the preferred prophylactic agent, as ephedrine crosses the placental barrier more than phenylephrine and is associated with a mild fetal acidemia of unknown significance.2,6 The Society for Obstetric Anesthesia and Perinatology Enhanced Recovery After Cesarean Delivery guidelines recommend prophylactic phenylephrine infusion to prevent hypotension. Studies have shown that a low-dose infusion of phenylephrine reduces the incidence of hypotension and nausea after spinal from 40% to less than 10%. Small doses of ephedrine can be used to treat hypotension in women with lower HR, and bradycardia can be treated with anticholinergic drugs.2 Emerging evidence suggest that norepinephrine, with its mild β-adrenergic activity, maintains cardiac output and may be potentially more effective in preventing hypotension without bradycardia.4,7,8


  • To reduce the incidence and severity of hypotension following induction of spinal anesthesia.

  • To maintain maternal systolic blood pressure (SBP) ≥90% of a known baseline, or >100 mm Hg if a baseline is unknown.

  • To improve recovery and prevent adverse maternal and neonatal effects of hypotension, such as intraoperative nausea and vomiting and fetal acidosis.


  • Intravenous (IV) fluid bolus of 10 to 15 mL/kg may be administered as a coload during spinal anesthesia, as discussed above, if there are no contraindications. We recommend using an in-line fluid warmer when administering a coload bolus.

  • Aortocaval compression should be avoided by placing parturients in left uterine displacement position (30°) until the neonate has been delivered.

  • Closely monitor blood pressure (BP). Most cases will not have continuous BP measurement, and we recommend cycling the noninvasive BP cuff frequently until BP stabilizes.

  • Pharmacologic prophylaxis should be used. We recommend initiating a phenylephrine infusion at 0.5 mcg/kg/min (or 25-50 mcg/min) at the time of induction of spinal anesthesia. Frequent adjustments should be made to maintain SBP at target.

  • Pharmacologic therapy could include bolus doses of ephedrine and phenylephrine based on maternal HR and BP. Ephedrine 10 mg is preferred if HR <70 bpm and may also provide longer-lasting effects. Phenylephrine 100 to 200 mcg ...

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