Magnesium Sulfate in ACLS: When to Stop Administration

Indications and Contraindications

The American Heart Association recommends that magnesium sulfate should not be routinely used in ACLS and should be stopped immediately if administered for any indication other than torsades de pointes (polymorphic VT associated with long-QT interval) 1, 2
Magnesium sulfate is only indicated in ACLS for torsades de pointes, where it may be considered at a dose of 1-2g IV bolus diluted in 10mL D5W 2, 3
Routine administration of magnesium sulfate in cardiac arrest is not recommended (Class III: No Benefit; Level of Evidence C-LD) 2, 3
Multiple randomized clinical trials have consistently shown no benefit of magnesium administration for cardiac arrest with any presenting rhythm or specifically for VF/pVT cardiac arrest 4, 2
Four small randomized trials with a total of 444 patients showed no increase in ROSC or survival to hospital discharge with magnesium administration 4

The 2018 American Heart Association ACLS guidelines specifically state that magnesium should not be used routinely during cardiac arrest management 1, 5

For torsades de pointes, administer 1-2g IV magnesium sulfate diluted in 10mL D5W 3
Magnesium acts to prevent reinitiation of torsades rather than pharmacologically converting polymorphic VT 4, 2
The use of magnesium for torsades de pointes is supported by observational studies, though randomized controlled trials are lacking 2

If torsades de pointes (polymorphic VT with long QT): Consider magnesium sulfate 2
If any other rhythm (VF, pVT, asystole, PEA): Do NOT administer magnesium 1, 2
If magnesium was started inappropriately: Stop administration immediately 1, 2
If torsades de pointes is present: Administer 1-2g IV magnesium sulfate diluted in 10mL D5W 3

The American Heart Association recommends intravenous magnesium sulfate (1-2g IV bolus) as first-line therapy for patients with torsades de pointes, especially when associated with QT interval prolongation 6, 7
Magnesium is effective for torsades de pointes regardless of baseline serum magnesium levels 8

The American College of Cardiology recommends 1-2g IV magnesium sulfate diluted in 10mL D5W for torsades de pointes 6

For patients taking QT-prolonging medications who present with few episodes of torsades de pointes and persistent QT prolongation, intravenous magnesium sulfate administration is reasonable, according to the American Heart Association 9, 7
If torsades de pointes persists despite magnesium administration, increasing heart rate with atrial or ventricular pacing or isoproterenol is recommended by the American College of Cardiology 7

The American Heart Association recommends against routine administration of magnesium sulfate in cardiac arrest unless torsades de pointes is present (Class III, LOE A) 6

For pediatric patients with torsades de pointes, the American Heart Association recommends administering 25-50 mg/kg IV/IO over 10-20 minutes, with a maximum single dose of 2g, and can be given more rapidly than the standard 10-20 minute timeframe 10

The American Heart Association has a Class III recommendation (No Benefit) for administering magnesium for VF, pulseless VT, asystole, or PEA, as multiple randomized trials with 444 patients showed no benefit for ROSC or survival to hospital discharge, however this fact is not directly cited with a reference id.

The European Society of Cardiology recommends intravenous magnesium sulfate for patients presenting with long QT syndrome and torsades de pointes, even with few episodes, with a Class IIa recommendation 11
The American Heart Association suggests administering 1-2 grams IV bolus diluted in 10 mL D5W over 1-2 minutes for torsades de pointes 12
Magnesium is effective in suppressing episodes of torsades de pointes regardless of baseline serum magnesium levels, and its mechanism involves suppressing episodes without necessarily shortening the QT interval, according to the European Heart Journal 12, 13
For patients on QT-prolonging medications who develop torsades de pointes with persistent QT prolongation, the American College of Cardiology recommends magnesium sulfate as the first-line therapy, and always withdrawing the offending agent and correcting electrolyte abnormalities (Class I recommendation) 11, 12

The European Heart Journal recommends identifying the VT type, and if polymorphic VT with prolonged QT (torsades de pointes), proceeding to administer magnesium sulfate 1-2 grams IV over 1-2 minutes, and repleting potassium to 4.5-5.0 mEq/L 11, 12, 13
For confirmed torsades de pointes, the European Society of Cardiology recommends immediately withdrawing any QT-prolonging drugs (Class I), administering magnesium sulfate, and monitoring for recurrence 11, 12

The American Heart Association notes that magnesium toxicity occurs at 6-8 mEq/L, but is extremely rare with standard 1-2 gram doses, and it is safe to administer even in patients with normal baseline magnesium levels 12