What is the first medication to give to a patient with hyperkalemia (elevated potassium levels) and hypotension (low blood pressure) presenting with a syncopal episode (fainting)?

Calcium Should Be Given First

For a hemodialysis patient presenting with syncope, bradycardia (heart rate 48), hypotension (BP 80/40), and altered mental status, intravenous calcium must be administered immediately to stabilize the cardiac membrane against hyperkalemia-induced arrhythmias. 1

Clinical Reasoning

This patient's presentation is classic for severe hyperkalemia with cardiac toxicity:

• Bradycardia and hypotension in a dialysis patient strongly suggest hyperkalemia affecting cardiac conduction 1
• Altered mental status ("slow to answer questions") indicates severe electrolyte derangement 2
• Syncope suggests a preceding arrhythmic event 1

The ECG (though not shown in detail) likely demonstrates hyperkalemic changes such as peaked T waves, widened QRS, prolonged PR interval, or flattened P waves—all of which mandate urgent calcium administration regardless of the exact potassium level 1, 3

Why Calcium First?

Calcium provides immediate cardiac membrane stabilization within 1-3 minutes, protecting against life-threatening arrhythmias and cardiac arrest. 1, 3 This is the only intervention that directly antagonizes the cardiac effects of hyperkalemia, though it does not lower the potassium level itself 1, 4

Dosing Options:

• Calcium chloride 10%: 5-10 mL (500-1000 mg) IV over 2-5 minutes (preferred for central access) 1
• Calcium gluconate 10%: 15-30 mL IV over 2-5 minutes (safer for peripheral IV due to lower tissue injury risk if extravasation occurs) 1

Calcium chloride provides more rapid increase in ionized calcium and is more effective in critically ill patients, but requires central access when possible 1

Why Not the Other Options?

B. Calcium (CORRECT ANSWER)

This is the first-line treatment as explained above.

A. Albuterol

While nebulized albuterol (10-20 mg over 15 minutes) does shift potassium intracellularly with onset in 15-30 minutes 1, it does not provide immediate cardiac protection. The patient's bradycardia and hypotension indicate imminent cardiac arrest risk requiring immediate membrane stabilization 1, 2

C. Lidocaine

Lidocaine is an antiarrhythmic that has no role in hyperkalemia management and does not address the underlying electrolyte disturbance 1, 3

D. Magnesium

Magnesium is used for torsades de pointes and certain other arrhythmias, but is not indicated for hyperkalemia-induced bradycardia. In fact, calcium is specifically recommended for magnesium intoxication, not the reverse 4

Complete Management Algorithm After Calcium

Once cardiac membrane is stabilized with calcium 1:

1. Shift potassium intracellularly (onset 15-30 minutes, duration 4-6 hours):

   • Insulin 10 units regular IV + 25g dextrose (50 mL D50W) 1
   • Nebulized albuterol 10-20 mg over 15 minutes 1
   • Sodium bicarbonate 50 mEq IV over 5 minutes ONLY if metabolic acidosis present 1, 3

2. Remove potassium from body:

   • Hemodialysis is the definitive treatment for this dialysis patient with severe hyperkalemia 1, 3
   • Loop diuretics are ineffective in dialysis-dependent patients 1

3. Monitor and reassess:

   • Continuous cardiac monitoring mandatory 1, 3
   • Repeat calcium dose if no ECG improvement within 5-10 minutes 1, 3
   • Check potassium every 2-4 hours during acute phase 3

Critical Pitfalls to Avoid

• Never delay calcium administration while waiting for laboratory confirmation if ECG changes or cardiac instability are present 3
• Do not use sodium bicarbonate without documented metabolic acidosis—it is ineffective and wastes critical time 1, 3
• Remember calcium is temporizing only (lasts 30-60 minutes)—definitive treatment with dialysis must follow 1, 3
• Monitor for hypoglycemia if insulin is given, especially in dialysis patients with altered metabolism 1
• Calcium effects are temporary—rebound hyperkalemia can occur, requiring repeat dosing or transition to dialysis 1, 3