NCLEX Question of the Day

Today’s question targets early recognition of magnesium sulfate toxicity in obstetric nursing. This matters because magnesium sulfate is commonly used to prevent seizures in clients with preeclampsia, but it can become dangerous if the nurse misses subtle signs of worsening toxicity. In real practice, quick assessment and prompt action protect both the pregnant client and the fetus.

Clinical Scenario

A 29-year-old client who is 33 weeks pregnant is admitted to the labor and delivery unit with severe preeclampsia. Her blood pressure is 168/104 mm Hg, and she has a persistent frontal headache and 3+ protein on urine dipstick. The provider prescribes a magnesium sulfate infusion for seizure prevention. Four hours after the infusion begins, the nurse notes the following: respiratory rate 10/min, urine output 20 mL over the last hour, the client reports feeling very sleepy, and deep tendon reflexes are difficult to elicit. Fetal heart rate is 140/min with moderate variability.

The Question

Which action should the nurse take first?

Answer Choices

1. Slow the magnesium sulfate infusion and recheck the client in 30 minutes.
2. Place the client in high-Fowler position and encourage deep breathing.
3. Stop the magnesium sulfate infusion and prepare to administer calcium gluconate.
4. Notify the provider that the fetal heart rate is within expected range.

Correct Answer

C. Stop the magnesium sulfate infusion and prepare to administer calcium gluconate.

Detailed Rationale

This client is showing classic signs of magnesium sulfate toxicity. The key findings are a respiratory rate of 10/min, low urine output, increasing sedation, and decreased deep tendon reflexes. Those findings matter because magnesium is excreted by the kidneys. When urine output falls, magnesium can build up in the body. As the level rises, the nervous system and respiratory system become depressed.

The nurse’s first priority is airway and breathing. A respiratory rate of 10/min is unsafe in a client receiving magnesium sulfate. The absent or diminished reflexes strengthen the concern that this is not just fatigue. It is a medication-related complication that can progress to respiratory arrest if the infusion continues.

The correct first action is to stop the magnesium sulfate infusion right away. This removes the source of the problem. Then the nurse should prepare to administer calcium gluconate, which is the antidote for magnesium toxicity. Calcium gluconate helps reverse the effects of excess magnesium on the heart, muscles, and respiratory system.

After stopping the infusion, the nurse should rapidly continue the assessment and response:

• Assess respiratory status closely, including rate, depth, and oxygen saturation.
• Apply oxygen if indicated by the client’s condition or unit protocol.
• Check level of consciousness.
• Confirm urine output and review recent intake and output trends.
• Reassess deep tendon reflexes.
• Notify the provider or rapid response team based on severity and facility policy.
• Prepare emergency equipment in case respiratory support is needed.
• Continue fetal monitoring because maternal instability can affect fetal oxygenation.

It is also important to understand why these assessments are routine during magnesium therapy. Nurses monitor respiratory rate, reflexes, and urine output because they are early bedside signs of toxicity. This is practical nursing surveillance, not just a checklist. A client can look calm and still be heading toward a crisis.

In many units, the nurse is expected to question magnesium administration if urine output is below 30 mL/hr, respirations are below 12/min, or reflexes are absent. Those are not minor changes. They suggest the body is no longer clearing the drug safely or is already being affected by it.

Why the Other Options Are Wrong

A. Slow the magnesium sulfate infusion and recheck the client in 30 minutes.

This is unsafe because the client already has signs of toxicity. Waiting 30 minutes could allow further respiratory depression. The nurse should stop, not reduce, the infusion.

B. Place the client in high-Fowler position and encourage deep breathing.

Positioning may slightly support breathing, but it does not address the cause of the problem. The priority is to stop the medication causing respiratory depression. Supportive measures can be added after the infusion is stopped.

D. Notify the provider that the fetal heart rate is within expected range.

The fetal status is reassuring right now, but this is not the priority. Maternal stabilization comes first. If the mother’s respiratory status worsens, fetal compromise may follow.

Key Takeaways

• Magnesium sulfate is used in preeclampsia to prevent seizures, but toxicity can depress the respiratory and nervous systems.
• Early warning signs include respiratory rate less than 12/min, decreased or absent deep tendon reflexes, low urine output, and increasing sedation.
• Low urine output matters because magnesium is cleared by the kidneys.
• The antidote for magnesium toxicity is calcium gluconate.
• In maternal emergencies, stabilize the mother first. Fetal well-being depends on maternal oxygenation and circulation.

• On-shift mini-checklist:
• Check respiratory rate before and during magnesium therapy.
• Trend urine output hourly.
• Assess reflexes regularly.
• Watch for new lethargy, weakness, or slowed breathing.
• If toxicity is suspected, stop the infusion, call for help, and prepare calcium gluconate.

Quick Practice Extension

1. A postpartum client receiving magnesium sulfate has a respiratory rate of 14/min, present reflexes, and urine output of 35 mL/hr. Which finding should the nurse report first if it appears next: blurred vision, flushing, nausea, or absent patellar reflexes?

2. A pregnant client with preeclampsia asks why the nurse keeps checking reflexes and urine output during magnesium therapy. How would you explain this in one clear, patient-friendly sentence?

Category used today: OB.

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