A pregnant woman on magnesium sulfate for severe pre-eclampsia becomes unresponsive, stops breathing, and her BP is 80/50 mmHg. Deep tendon reflexes are absent. Serum magnesium level is 12 mEq/L. What is the immediate management priority?
- A IV calcium gluconate 1 g over 3 minutes ✓
- B Stop magnesium and administer IV furosemide
- C Intubate and ventilate without antidote
- D Administer IV atropine sulfate
Correct answer: A. IV calcium gluconate 1 g over 3 minutes
Explanation
At serum magnesium > 10 mEq/L, respiratory arrest and cardiovascular collapse can occur. The specific antidote for magnesium toxicity is calcium gluconate 1 g (10 mL of 10% solution) given IV over 3 minutes, which directly antagonises magnesium at voltage-gated calcium channels. Furosemide enhances renal magnesium excretion but is too slow for acute arrest. Intubation alone without reversing the toxin is insufficient when an antidote exists. Atropine has no role in magnesium toxicity.
Reference: Williams Obstetrics, 26th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.