A nurse is monitoring a laboring client at 40 weeks gestation. The fetal heart rate tracing shows a baseline of 140 bpm with moderate variability. During the last three contractions, the nurse observes late decelerations that begin after the peak of the contraction and return to baseline after the contraction ends. The client's blood pressure is 90/60 mmHg, and she reports feeling dizzy when lying flat. What is the nurse's priority action?
1Administer oxygen at 8-10 L/min via face mask
2Position the client in left lateral position✓ 정답
3Increase the IV fluid infusion rate
4Prepare for immediate cesarean delivery
해설
Late decelerations with supine hypotension suggest vena cava compression. Positioning in left lateral relieves this and improves placental blood flow, making it the priority over other interventions.
Understanding the Clinical Picture
The scenario describes a classic case of supine hypotensive syndrome, also known as aortocaval compression. The client is at full term (40 weeks), and the heavy gravid uterus compresses the maternal great vessels when she lies flat. This compression reduces venous return to the heart, leading to decreased cardiac output and maternal hypotension (noted here as 90/60 mmHg) and dizziness. The fetal consequence of this maternal hemodynamic compromise is uteroplacental insufficiency, which manifests on the fetal heart rate (FHR) tracing as late decelerations.
Analyzing the Fetal Heart Rate Pattern
The baseline FHR of 140 bpm with moderate variability is reassuring, indicating that the fetal central nervous system is well-oxygenated and not acidotic at its baseline. However, the presence of late decelerations is a non-reassuring sign. Late decelerations are caused by a transient drop in fetal oxygen saturation during a uterine contraction. In a compromised uteroplacental unit, the contraction further reduces blood flow, and the fetal pO2 drops below a critical threshold, triggering chemoreceptor-mediated vagal slowing of the FHR. The deceleration begins after the peak of the contraction and returns to baseline after the contraction ends, reflecting the time lag in this hypoxic reflex pathway.
Establishing the Priority Action
The nurse’s priority is to correct the underlying cause of the late decelerations. The evidence clearly links the maternal supine position to the observed pathophysiology. A 2025 scoping review by Hammes et al. summarizes that the maternal supine position may reduce uterine and placental perfusion due to compression of the aorta and inferior vena cava, potentially impairing maternal and fetal oxygenation [2]. This directly explains the late decelerations seen on the monitor. The client’s report of dizziness and low blood pressure are the maternal clinical correlates of this compression.
Therefore, the immediate and most effective intervention is to relieve the aortocaval compression by repositioning the client. The left lateral position is the standard of care because it shifts the weight of the uterus off the inferior vena cava and aorta, which run along the right side of the vertebral column. This action directly addresses the root cause of the reduced placental perfusion. While administering oxygen (Option 1) and increasing IV fluids (Option 3) are common intrauterine resuscitation measures, they are secondary and supportive. They will be less effective if the primary mechanical obstruction to blood flow is not first removed. Preparing for immediate cesarean delivery (Option 4) is premature; late decelerations caused by maternal position are often completely resolved with a simple position change, and the presence of moderate variability suggests the fetus is not yet in a terminal state of hypoxia. The research by O'Brien and Warland further supports this, noting that maternal supine posture in late pregnancy and labor is known to compromise maternal hemodynamics and subsequently affect the fetus . Repositioning the client to a left lateral position is the definitive first-line nursing action to reverse this sequence of events.
References (research sources)
[2]
How maternal position affects umbilical and middle cerebral artery Doppler indices: insights from a scoping review.Research articleHammes LR, Miyague AH, Nisihara RM. (2025) · DOI: 10.61622/rbgo/2025rbgo45
Clinical Case: Supine Hypotensive Syndrome with Late Decelerations
Scenario: A laboring client at 40 weeks gestation reports dizziness when lying flat. Her blood pressure is 90/60 mmHg, and the fetal monitor shows a baseline of 140 bpm with moderate variability but recurrent late decelerations during contractions.
Nurse's Priority Action
The immediate priority is to relieve aortocaval compression by repositioning the client to a left lateral position. This simple maneuver shifts the weight of the gravid uterus off the maternal inferior vena cava and aorta, restoring venous return, increasing cardiac output, and improving placental perfusion. Resolution of late decelerations following this intervention confirms the diagnosis of supine hypotensive syndrome.
Clinical Rationale
Pathophysiology: The gravid uterus compresses the great vessels, reducing preload and causing maternal hypotension. This leads to uteroplacental insufficiency, which manifests as late decelerations on the fetal heart rate tracing.
FHR Interpretation: Moderate variability indicates a non-acidotic fetus at baseline, but late decelerations signify a transient hypoxic event during contractions due to compromised placental blood flow.
Intervention Hierarchy: Intrauterine resuscitation begins with the least invasive, most targeted intervention. Lateral positioning directly reverses the mechanical cause of the decelerations and is the first-line action before considering oxygen administration, IV fluid bolus, or operative delivery.
Intrauterine Resuscitation Protocol (ILO PAVE)
I - Initiate Lateral Positioning: Turn the client to a left or right lateral position to relieve aortocaval compression.
L - Lactated Ringer's Bolus: Administer an IV fluid bolus as ordered to correct maternal hypotension if positioning alone is insufficient.
O - Oxygen Administration: Apply oxygen at 10 L/min via a non-rebreather mask if late decelerations persist despite other measures.
P - Pitocin (Oxytocin) Adjustment: Notify the provider and consider reducing or discontinuing oxytocin to decrease uterine contraction frequency and resting tone.
A - Assess and Notify: Continuously reassess maternal vital signs and FHR tracing, and notify the healthcare provider promptly.
V - Vasopressors: Administer vasopressors (e.g., ephedrine) as ordered for refractory maternal hypotension.
E - Expedite Delivery: Prepare for operative delivery if resuscitation measures fail to resolve the non-reassuring fetal status.
Late Decelerations — Fetal heart rate decreases that begin after the peak of a contraction and return to baseline after the contraction ends, indicating uteroplacental insufficiency.
Supine Hypotensive Syndrome — A condition in late pregnancy where the gravid uterus compresses the inferior vena cava and aorta when the mother lies flat, reducing venous return and causing hypotension.
Moderate Variability — Fluctuations in the baseline fetal heart rate of 6 to 25 beats per minute, indicating an intact and well-oxygenated fetal central nervous system.
Uteroplacental Insufficiency — A reduction in blood flow through the placenta, leading to decreased fetal oxygenation and the potential for non-reassuring fetal heart rate patterns.