Case: 74 years old male has been found to have arrhythmia with runs of wide complex ventricular tachycardia. The patient so far has remained hemodynamically stable. A crash cart is called near the bed, pads are applied to the chest, and STAT labs are sent. A review of the chart showed that: 4 days ago digoxin level was 1.9, and since then patient's serum creatinine level is steadily rising from 1.6 to 2.8. "Dig. toxicity" is suspected. STAT dig. level is ordered. Indeed, Dig. level is back with 3.4, and accompanied labs showed a K+ level of 6.9. "Digi-bind" (Digoxin Immune Fab) is ordered. Interim, the medical resident, ordered the following regimen to treat hyperkalemia: IV insulin, D-50, IV bicarb., IV calcium, and albuterol neb.. Pharmacy informed, "IV calcium is not available." What other electrolytes can be used instead of calcium to stabilize the cardiac membrane in hyperkalemia?
Answer: IV Magnesium
Some literature has shown a similar membrane stabilizing effect from magnesium and may be used instead of calcium in hyperkalemia.
Also, caution should be sought not to treat hyperkalemia aggressively, or at least the potassium level should be followed very closely, particularly when DigiFab administration is planned.
Digoxin causes a shift of potassium from inside to outside of the cell and may cause severe serum hyperkalemia, though overall, there is a whole-body deficit of potassium. With the administration of DigiFab (Digibind), potassium shifts back into the cell, and life-threatening serum hypokalemia may ensue rapidly.
#cardiology
#pharmacology
References:
1. Slow-release potassium overdose: Is there a role for magnesium? Emergency Medicine 1999;11:263–71
2. Kinlay S, Buckley NA. Magnesium sulfate in the treatment of ventricular arrhythmias due to digoxin toxicity. J Toxicol Clin Toxicol. 1995;33(1):55-9. doi: 10.3109/15563659509020216. PMID: 7837314.
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