Which of the following noted on the assessment of a pregnant mother receiving magnesium sulfate for the management of preeclampsia, determines that the client is experiencing toxicity?

1. A

   Respirations of 10 breaths/min

2. B

   Serum magnesium level of 6 mEq/L

3. C

   Presence of deep tendon reflexes

4. D

   Proteinuria of $3\div$

Appeared in: DSSSB - 28 August 2019 (Shift-1)

Explanation

• Magnesium sulfate is a central nervous system (CNS) depressant used for seizure prophylaxis in preeclampsia.
• Respiratory depression is a critical, life-threatening sign of magnesium sulfate toxicity.
• A respiratory rate of 10 breaths/min is below the threshold of 12 breaths/min, indicating significant toxicity that requires immediate intervention.

Why Other Options Were Wrong

• Option B: A serum magnesium level of 6 mEq/L falls within the established therapeutic range of 4-7 mEq/L for seizure prevention.
• Option C: The presence of deep tendon reflexes (DTRs) is a normal finding. The loss or absence of DTRs is an early sign of magnesium toxicity.
• Option D: Proteinuria is a diagnostic criterion and a sign of the severity of preeclampsia itself, caused by endothelial damage to the kidneys.

Related Visual

Clinical Relevance

• Nursing practice connection: Use the key finding related to Assessment of Magnesium Sulfate Toxicity to guide bedside assessment, documentation, and the next nursing action.
• Nurses must perform frequent assessments (every 1-2 hours) of respiratory rate, deep tendon reflexes, level of consciousness, and urine output for any patient receiving magnesium sulfate.
• The antidote for magnesium sulfate toxicity, calcium gluconate, must be readily available at the bedside for immediate administration in an emergency.
• What if the patient had pre-existing renal impairment (e.g., serum creatinine greater than 1.0 mg/dL)? The risk of toxicity would be much higher because magnesium is cleared by the kidneys. The maintenance dose would need to be reduced, and serum magnesium levels would be monitored more frequently.

How to Approach the Question

• First, identify the core of the question: it's asking for a sign of toxicity from a specific drug, magnesium sulfate.
• Recall the primary action of magnesium sulfate: it's a CNS depressant.
• List the known signs of magnesium sulfate toxicity in order of severity: loss of deep tendon reflexes (early), followed by respiratory depression (late/severe), and finally cardiac arrest (lethal).
• Evaluate each option against this knowledge.
• Option A (Respirations 10/min) directly matches the sign of respiratory depression (rate < 12/min).
• Option B (Mg level 6 mEq/L) is within the therapeutic range (4-7 mEq/L), so it's incorrect.

Concept Tested & Keywords

• Concept Tested: Assessment of Magnesium Sulfate Toxicity
• Stem keywords: magnesium sulfate, preeclampsia, toxicity, assessment, pregnant mother
• Lead-in keywords: determines, experiencing toxicity
• Clinical cues: Age/sex group narrows the expected diagnosis, intervention, or normal reference range.
• Negative lead-in flag: false

Question ID

QTvMWqjJsJKRbxejEQfNEO

Copy ID

Reference Book

E6 Obstetrics Williams p. 31-51