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Difficulty: MediumLabor, Delivery, and Puerperium

A 24-year-old nulliparous patient presents to the labor unit at 39 weeks and 4 days of gestation with painful uterine contractions. Her prenatal course was unremarkable. On admission, her cervical examination demonstrates 5 cm of dilation, 90% effacement, and -1 station. Two hours later, she requests neuraxial analgesia, and a continuous epidural infusion is successfully initiated. Shortly after the procedure, the patient complains of dizziness and nausea. Her blood pressure drops to 80/45 mm Hg from a baseline of 118/74 mm Hg, and her heart rate increases to 112/min. Concurrently, the continuous fetal monitor demonstrates a sudden decrease in the fetal heart rate baseline from 145/min to 85/min, which persists for 4 minutes with minimal variability. The nursing staff immediately places the patient in the left lateral decubitus position and administers a rapid intravenous bolus of isotonic crystalloid, but her blood pressure only marginally improves to 84/48 mm Hg. The fetal heart rate remains at 85/min. Which of the following is the most appropriate next step in the management of this patient?

  1. Intravenous ephedrineAnswer
  2. B
    Emergency cesarean delivery
  3. C
    Transcervical amnioinfusion
  4. D
    Subcutaneous terbutaline
  5. E
    Intravenous oxytocin

Answer

Intravenous ephedrine
The correct answer is intravenous ephedrine. The patient has developed maternal hypotension secondary to epidural anesthesia. Epidurals cause sympathetic blockade, which leads to peripheral vasodilation, pooling of blood in the lower extremities, and reduced venous return. This cascade decreases maternal cardiac output and placental perfusion, resulting in fetal hypoxia and a prolonged fetal heart rate deceleration. Initial management of post-epidural hypotension includes maternal repositioning (specifically left lateral uterine displacement to relieve aortocaval compression) and a rapid intravenous fluid bolus. Because these conservative measures were insufficient to restore maternal blood pressure in this patient, the most appropriate next step is the administration of a vasopressor, such as intravenous ephedrine or phenylephrine. Restoring maternal blood pressure will resolve the uteroplacental insufficiency and typically leads to the rapid recovery of the fetal heart rate.

Step-by-Step Solution

1
Identify the cause of the fetal heart rate deceleration.
The patient developed severe hypotension immediately following the initiation of epidural analgesia.
Sympathetic blockade from the epidural causes vasodilation and decreased venous return, leading to reduced maternal cardiac output, diminished placental perfusion, and a prolonged fetal deceleration.
2
Evaluate the interventions already performed.
The patient was repositioned to the left lateral decubitus position and received an intravenous fluid bolus.
These are the initial non-pharmacologic steps to relieve aortocaval compression and increase preload, attempting to restore maternal blood pressure.
3
Determine the next appropriate step for refractory maternal hypotension.
Administer a vasopressor such as intravenous ephedrine or phenylephrine.
Restoring maternal blood pressure with a vasopressor is necessary to resolve the uteroplacental insufficiency and the fetal deceleration, and must be attempted before considering operative delivery.

Key Concept

The management of prolonged fetal heart rate decelerations secondary to post-epidural maternal hypotension involves sequential intrauterine resuscitation: maternal repositioning, intravenous fluid boluses, and if refractory, the administration of a vasopressor (ephedrine or phenylephrine).
Estimated Time:1m 30s
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Topics

Labor, Delivery, and Puerperium

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