Calcium Gluconate for Hypotension
Calcium gluconate (or calcium chloride) is NOT recommended for general hypotension management, but IS specifically indicated for hypotension caused by calcium channel blocker overdose or when associated with documented hypocalcemia. 1, 2
Specific Clinical Indications
Calcium Channel Blocker-Induced Hypotension
- Calcium chloride is recommended for calcium channel blocker-induced hypotension that is refractory to fluid resuscitation and standard vasopressors (Class IIb recommendation). 1
- Administer calcium chloride 20 mg/kg (0.2 mL/kg of 10% solution) IV over 5-10 minutes as initial bolus, followed by continuous infusion of 20-50 mg/kg per hour if beneficial effect occurs. 1
- However, high-dose insulin-euglycemia therapy has stronger evidence (Class IIb, LOE B) and should be prioritized over calcium administration for calcium channel blocker toxicity. 1, 2
- For β-blocker-induced shock refractory to other measures, calcium may be considered but evidence is weaker than for calcium channel blocker toxicity (Class IIb, LOE C). 1
Hypocalcemia-Associated Hypotension
- Hypocalcemia is a clinically significant cause of refractory hypotension, with vasopressor support required in 41% of hypocalcemic patients compared to 14% of normocalcemic patients. 3
- Ionized calcium <1.02 mmol/L is associated with significantly increased risk of severe hypotension (hazard ratio 2.9; 95% CI 1.5-5.7), particularly during continuous renal replacement therapy. 4
- Profound hypocalcemia can cause refractory hypotension and heart failure that improves dramatically after intravenous calcium administration, especially in patients with renal disease. 5
Administration Algorithm
Step 1: Identify the Cause
- Determine if hypotension is due to calcium channel blocker overdose, documented hypocalcemia (ionized calcium <1.02 mmol/L), or other causes. 1, 4
- For calcium channel blocker overdose: initiate fluid resuscitation, start vasopressors (norepinephrine 0.1-0.5 mcg/kg/min), and prioritize high-dose insulin-euglycemia therapy (1 U/kg IV bolus, then 1-10 U/kg/h infusion). 2
Step 2: Calcium Administration (If Indicated)
- Use calcium chloride rather than calcium gluconate in critically ill patients because it produces more rapid increase in ionized calcium and contains 3 times more elemental calcium per volume. 1
- Administer via central venous access whenever possible to avoid severe skin and soft tissue injury from extravasation. 1
- Maintain continuous ECG monitoring during administration. 1
Step 3: Target First-Line Therapies
- For general hypotension: norepinephrine is first-line vasopressor targeting MAP ≥65 mmHg. 2, 6
- For intradialytic hypotension: increase dialysate calcium concentration, lower dialysate temperature to 34-35°C, or administer midodrine (oral α1-adrenergic agonist). 7
- For persistent hypotension post-carotid artery stenting: ephedrine 25-50 mg orally 3-4 times daily may be useful. 7
Critical Pitfalls to Avoid
- Do not use calcium for general undifferentiated hypotension without identifying calcium channel blocker toxicity or documented hypocalcemia as the cause. 1, 2
- Avoid peripheral IV administration of calcium chloride due to risk of severe tissue necrosis from extravasation. 1
- Do not delay vasopressor initiation (norepinephrine) while attempting calcium administration in general hypotension. 2, 6
- Do not use calcium as monotherapy for calcium channel blocker overdose; high-dose insulin therapy is more effective. 1, 2