Recommended Dose of Calcium for Emergency Cardiac Protection in Hyperkalemia
For emergency cardiac protection in hyperkalemia, administer calcium chloride (10%) 5-10 mL (500-1000 mg) IV over 2-5 minutes or calcium gluconate (10%) 15-30 mL IV over 2-5 minutes. 1
Mechanism of Action
Calcium administration rapidly antagonizes the effect of potassium on excitable cell membranes, particularly cardiac tissue, within 1-3 minutes of administration. This provides immediate cardiac protection by:
- Stabilizing myocardial cell membranes
- Reducing membrane excitability
- Counteracting the cardiotoxic effects of hyperkalemia
- Preventing cardiac arrhythmias
It's important to note that calcium administration does not significantly reduce serum potassium levels but rather protects the heart from the effects of hyperkalemia while other treatments work to lower potassium levels 1.
Calcium Salt Options
Two calcium salt formulations are commonly used:
Calcium Chloride (10%):
- Dose: 5-10 mL (500-1000 mg) IV
- Contains more elemental calcium per volume
- Results in more rapid increase in ionized calcium
- Preferred for critically ill patients and cardiac emergencies
- Administration through a central venous catheter is preferred
Calcium Gluconate (10%):
- Dose: 15-30 mL IV
- May be substituted if calcium chloride is not available
- Can be administered through a peripheral IV if necessary
- Contains less elemental calcium per volume
Administration Guidelines
- Rate of administration: Give by slow push for cardiac arrest; infuse over 30-60 minutes for other indications 1
- Monitoring: Monitor heart rate during administration and stop injection if symptomatic bradycardia occurs
- Repeat dosing: If no effect is observed within 5-10 minutes, another dose of calcium may be given 1
- Vascular access: Administration through a central venous catheter is preferred; extravasation through a peripheral IV line may cause severe skin and soft tissue injury 1
Pediatric Considerations
For pediatric patients with hyperkalemia requiring cardiac protection:
- Calcium chloride (10%): 20 mg/kg (0.2 mL/kg)
- Calcium gluconate can be substituted at a dose of 60 mg/kg if calcium chloride is not available 1
Important Precautions
- Vascular access: Use a secure IV line to avoid calcinosis cutis and tissue necrosis 2
- Incompatibilities: Do not mix calcium with:
- Ceftriaxone (can form precipitates)
- Fluids containing bicarbonate or phosphate
- Minocycline injection 2
- ECG monitoring: Continuous ECG monitoring is recommended during calcium administration
Complete Hyperkalemia Management
While calcium provides immediate cardiac protection, comprehensive management of hyperkalemia requires additional interventions:
Stabilize myocardial cell membrane:
- Calcium administration as detailed above
Shift potassium into cells:
- Sodium bicarbonate: 50 mEq IV over 5 minutes
- Glucose plus insulin: 25 g glucose (50 mL of D50) and 10 U regular insulin IV over 15-30 minutes
- Nebulized albuterol: 10-20 mg over 15 minutes
Promote potassium excretion:
- Diuresis: furosemide 40-80 mg IV
- Potassium-binding resins
- Dialysis if necessary 1
Evidence on Efficacy
Recent research has shown that IV calcium gluconate therapy is effective, albeit to a limited degree, in treating main rhythm ECG disorders due to hyperkalemia 3. The beneficial effects of calcium treatment for hyperkalemia appear to be through restoration of conduction via calcium-dependent propagation, rather than through "membrane stabilization" as previously thought 4.
Hyperkalemia should be suspected in any patient presenting with acute onset of hypotension and bradycardia, and IV calcium salts should be promptly administered for hemodynamic instability due to hyperkalemia 5.
Remember that calcium administration is recommended for cardiac resuscitation only in cases of documented hyperkalemia, hypocalcemia, hypermagnesemia, or calcium channel blocker toxicity 1.