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Difficulty: MediumLabor, Delivery, and Puerperium

A nulliparous patient at 39 weeks gestation is admitted to the labor unit and receives continuous lumbar epidural analgesia for pain control during the active phase of labor. Fifteen minutes after the epidural is activated, the patient reports feeling dizzy and nauseated. Her temperature is 37.0°C (98.6°F), blood pressure is 82/45 mm Hg, and heart rate is 112/min. The electronic fetal monitor reveals a baseline heart rate of 140/min, moderate variability, and recurrent gradual decreases in the fetal heart rate that reach their nadir after the peak of each uterine contraction. Uterine contractions are occurring every 4 minutes and lasting 60 seconds. The patient is immediately placed in the left lateral decubitus position, and a rapid bolus of intravenous lactated Ringer solution is administered. Five minutes later, her blood pressure is 84/48 mm Hg, and the fetal heart rate pattern remains unchanged. Which of the following is the most appropriate next step in management?

  1. Administration of intravenous ephedrineAnswer
  2. B
    Emergency cesarean delivery
  3. C
    Initiation of transcervical amnioinfusion
  4. D
    Administration of subcutaneous terbutaline
  5. E
    Observation with continued maternal monitoring

Answer

Administration of intravenous ephedrine
This patient is experiencing epidural-induced maternal hypotension, a common complication caused by the blockade of sympathetic nerve fibers, resulting in peripheral vasodilation and decreased venous return. The resulting drop in maternal blood pressure causes uteroplacental hypoperfusion, which manifests on the fetal monitor as recurrent late decelerations (gradual decreases in fetal heart rate that nadir after the peak of the contraction). The standard initial management for this condition—termed intrauterine resuscitation—includes maternal repositioning to the left lateral decubitus position (to relieve aortocaval compression) and a rapid intravenous fluid bolus (to increase intravascular volume). Because this patient's hypotension and fetal heart rate abnormalities remain refractory to these initial measures, the most appropriate next step is the administration of an intravenous vasopressor, such as ephedrine or phenylephrine. These agents induce vasoconstriction and increase cardiac output, thereby restoring maternal blood pressure and uteroplacental perfusion.

Step-by-Step Solution

1
Identify the primary maternal complication.
The patient has developed symptomatic maternal hypotension following the placement of epidural analgesia.
Epidural anesthesia blocks sympathetic fibers, leading to peripheral vasodilation, venous pooling, and subsequent decreased cardiac output and blood pressure.
2
Correlate maternal hypotension with fetal heart rate changes.
The fetal heart rate tracing shows late decelerations.
Maternal hypotension decreases uteroplacental perfusion, leading to transient fetal hypoxia and triggering late decelerations (gradual nadir occurring after the peak of the contraction).
3
Evaluate the response to initial resuscitative measures.
Left lateral positioning and an intravenous fluid bolus were administered but failed to correct the blood pressure or fetal heart rate pattern.
Initial mechanical and volume-based interventions are standard first steps but may be insufficient to overcome severe pharmacologic vasodilation.
4
Determine the next best pharmacological intervention.
Administration of a vasopressor (ephedrine or phenylephrine) is indicated.
Vasopressors constrict peripheral blood vessels and/or increase cardiac output, restoring maternal blood pressure and normalizing uteroplacental blood flow, thus resolving the late decelerations.

Key Concept

Epidural-induced maternal hypotension leading to late decelerations should be managed initially with repositioning and IV fluids, followed by a vasopressor (ephedrine or phenylephrine) if refractory.
Estimated Time:1m 0s
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Topics

Labor, Delivery, and Puerperium

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