What is the treatment for magnesium sulfate (MgSO4) poisoning?

Treatment for Magnesium Sulfate (MgSO4) Poisoning

The treatment for magnesium sulfate poisoning includes immediate administration of intravenous calcium (calcium chloride 10% 5-10 mL or calcium gluconate 10% 15-30 mL IV over 2-5 minutes), supportive care, and hemodialysis in severe cases. 1

Clinical Presentation of Magnesium Toxicity

• Hypermagnesemia is defined as a serum magnesium concentration >2.2 mEq/L (normal: 1.3 to 2.2 mEq/L) 1
• Neurological symptoms include muscular weakness, paralysis, ataxia, drowsiness, and confusion 1
• Cardiovascular manifestations include vasodilation, hypotension, bradycardia, and cardiac arrhythmias 1
• Respiratory depression and hypoventilation may occur at extremely high serum magnesium levels 1
• Progression to cardiorespiratory arrest is possible in severe cases 1, 2

First-Line Treatment

• Calcium administration: Intravenous calcium acts as a physiological antagonist to magnesium 1
  • Calcium chloride (10%) 5-10 mL IV over 2-5 minutes, OR
  • Calcium gluconate (10%) 15-30 mL IV over 2-5 minutes 1
• Discontinue any ongoing magnesium administration immediately 2
• Initiate cardiac monitoring and support vital functions 1
• Fluid therapy with normal saline to enhance renal excretion of magnesium 2

Supportive Measures

• Airway management and ventilatory support if respiratory depression is present 2
• Continuous cardiac monitoring for arrhythmias 1
• Correction of any other electrolyte abnormalities, particularly potassium 1
• Blood pressure support with vasopressors if hypotension persists despite calcium administration and fluid resuscitation 1

Advanced Treatment for Severe Cases

• Hemodialysis should be initiated promptly if:
  • Basic supportive interventions are ineffective 2
  • Patient has severe symptoms (cardiac arrhythmias, respiratory depression) 2
  • Extremely high serum magnesium levels persist 2
  • Patient has impaired renal function limiting magnesium excretion 2

Monitoring During Treatment

• Serial serum magnesium levels to guide therapy 2
• Continuous ECG monitoring for cardiac arrhythmias 1
• Frequent vital sign assessment, particularly respiratory rate and blood pressure 1
• Neurological status evaluation to track improvement in symptoms 1
• Renal function tests to assess kidney function and magnesium clearance 2

Special Considerations

• In pregnant patients with preeclampsia who received therapeutic magnesium sulfate, the same principles of treatment apply, but with careful attention to maternal and fetal monitoring 1
• In patients with renal impairment, hemodialysis should be considered earlier in the treatment course due to decreased ability to excrete magnesium 2
• For iatrogenic overdose (as in medication errors), identification of the exact dose administered helps guide the aggressiveness of treatment 2

Common Pitfalls to Avoid

• Delaying calcium administration while waiting for laboratory confirmation of hypermagnesemia when clinical signs strongly suggest magnesium toxicity 1
• Failing to consider hemodialysis early in severe cases or when conventional therapy is ineffective 2
• Overlooking the need for continuous cardiac monitoring during treatment 1
• Not recognizing that patients with renal dysfunction are at higher risk for prolonged magnesium toxicity and may require more aggressive intervention 2