A nurse is caring for a 28-year-old primigravida at 36 weeks' gestation who is receiving intravenous magnesium sulfate for severe preeclampsia. Which finding requires the nurse to immediately discontinue the magnesium infusion?
1Patellar reflexes 2+ and respiratory rate 16/min
2Urine output 40 mL/hr and blood pressure 150/95 mm Hg
3Patellar reflexes absent and respiratory rate 10/min✓ Correct answer
4Deep tendon reflexes 3+ and clonus present
Explanation
Absent patellar reflexes and a respiratory rate of 10/min indicate magnesium sulfate toxicity, which can progress to respiratory arrest. The nurse must immediately stop the infusion, provide respiratory support, notify the provider, and prepare to administer calcium gluconate as prescribed. Patellar reflexes 2+ and respiratory rate 16/min are normal findings. Urine output of 40 mL/hr is adequate, and a blood pressure of 150/95 mm Hg, while elevated, does not indicate toxicity. Deep tendon reflexes 3+ and clonus suggest central nervous system irritability, not magnesium toxicity.