Signs of magnesium sulfate toxicity:
• Diminished or absent deep tendon reflexes (first sign of toxicity)- hyporeflexia
• Respiratory depression- A respiratory rate <12 breaths/min is a critical sign of toxicity.
• Decreased urine output- <30 mL/hour
In this scenario, a respiratory rate of 10/min is the most alarming sign of toxicity.
Management of magnesium sulfate toxicity:
• Discontinue magnesium sulfate immediately.
• Administer calcium gluconate (10 mL of 10% solution IV) as an antidote to counteract its effects.
• Monitor serum magnesium and creatinine levels closely.
• Provide respiratory support if needed.