In preeclampsia with magnesium sulfate, a respiratory rate of 10 with deep tendon reflexes of 0 indicates magnesium toxicity. What is the priority action?

• A. Place client in Trendelenburg position and apply oxygen
• B. Stop magnesium and prepare to give calcium gluconate
• C. Ask another nurse to verify the deep tendon reflexes
• D. Prepare client for an emergency cesarean section

Answer: (B)

Magnesium sulfate toxicity presents with respiratory depression and loss of deep tendon reflexes because magnesium dampens neuromuscular transmission and CNS function. The priority is to halt the offending agent and reverse its effect. Stop the magnesium infusion immediately and prepare to administer calcium gluconate, the specific antidote that antagonizes magnesium’s actions. Have resuscitation equipment ready and monitor the patient’s airway, breathing, and circulation closely while the antidote is prepared and given per protocol.

Other actions don’t directly reverse the toxicity or stop further magnesium from accumulating: repositioning or giving oxygen doesn’t address the underlying magnesium excess; confirming reflexes delays life-saving treatment; and proceeding to an emergency cesarean section is only warranted for obstetric indications, not the immediate management of magnesium toxicity.