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Zorluk: OrtaObstetric Complications

An obstetrics triage nurse evaluates a primigravid patient at 40 weeks and 2 days gestation. The patient was admitted earlier in the day for an elective labor induction and is currently receiving an intravenous infusion of oxytocin. She reports severe, sharp pain with each contraction, and monitoring shows contractions occurring every 2.5 minutes on average. Vital signs include a blood pressure of 118/76 mm Hg, heart rate of 88/min, and respiratory rate of 18/min. To investigate a complaint of mild shortness of breath, an arterial blood gas on room air is drawn, demonstrating a pH of 7.44, PaCO₂ of 28 mm Hg, and PaO₂ of 102 mm Hg.

A continuous fetal heart rate monitor displays a baseline rate of 140/min accompanied by moderate variability. However, the tracing also reveals recurrent, symmetric decreases in the heart rate to a nadir of 120/min. The onset of each decrease is gradual, taking roughly 40 seconds to reach its lowest point. Notably, the nadir of each deceleration occurs consistently after the peak of the corresponding uterine contraction, returning to baseline only after the contraction ends. These specific decelerations are present following 60% of the recorded contractions. Pelvic examination confirms the cervix is 5 cm dilated and 90% effaced, with the fetal head at 0 station.

Based on these findings, which of the following is the most appropriate next step in management?

  1. Discontinue the intravenous oxytocin infusionCevap
  2. B
    Proceed directly to an emergent cesarean delivery
  3. C
    Perform an amnioinfusion
  4. D
    Maintain the current management and reassure the patient
  5. E
    Instruct the patient to breathe into a paper bag to correct respiratory alkalosis

Cevap

Discontinue the intravenous oxytocin infusion
The correct action is to discontinue the intravenous oxytocin infusion. The patient's fetal heart rate tracing is highly characteristic of recurrent late decelerations. A late deceleration is defined as a visually apparent, gradual decrease in the fetal heart rate (onset to nadir taking ≥ 30 seconds) where the nadir occurs after the peak of the uterine contraction. These decelerations occur due to uteroplacental insufficiency. When late decelerations are recurrent (occurring with ≥ 50% of uterine contractions), they signal a disruption in fetal oxygenation. The immediate first-line management is intrauterine resuscitation, which aims to optimize uteroplacental blood flow. Essential steps include maternal repositioning (e.g., left lateral decubitus), administering an intravenous fluid bolus, providing supplemental oxygen, and discontinuing uterotonic agents. Stopping oxytocin immediately reduces the frequency and intensity of contractions, relieving the stress on the uteroplacental circulation.

Adım Adım Çözüm

1
Analyze the fetal heart rate tracing.
Identify recurrent late decelerations, characterized by a gradual onset and a nadir that occurs after the peak of the uterine contraction.
Accurate interpretation of decelerations is critical to determining the underlying etiology of fetal distress.
2
Determine the pathophysiology behind the tracing abnormality.
Correlate late decelerations with uteroplacental insufficiency, which causes transient fetal hypoxemia during contractions.
Understanding the mechanism dictates the appropriate physiological intervention.
3
Evaluate the maternal vital signs and laboratory findings.
Recognize that the mild respiratory alkalosis (pH 7.44, low PaCO2) is a normal physiological adaptation to pregnancy and does not require treatment.
Distinguishing physiological changes of pregnancy from pathological states prevents unnecessary and distracting interventions.
4
Select the most appropriate initial management step.
Choose to discontinue the oxytocin infusion as part of initial intrauterine resuscitation.
Stopping uterotonic agents decreases the frequency and intensity of contractions, allowing uteroplacental blood flow and fetal oxygenation to recover.

Anahtar Kavram

Recurrent late decelerations indicate uteroplacental insufficiency and must be initially managed with intrauterine resuscitation, including the discontinuation of uterotonics.
Tahmini Süre:1m 30s
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Konular

Obstetric Complications

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