From the Guidelines
Calcium is administered in hypotension to improve cardiovascular function and blood pressure, particularly in cases of calcium channel blocker overdose, hyperkalemia, hypermagnesemia, and cardiopulmonary resuscitation, as recommended by the 2023 American Heart Association guidelines update 1.
Clinical Scenarios for Calcium Administration
The administration of calcium in hypotension is considered in specific clinical scenarios, including:
- Calcium channel blocker overdose
- Hyperkalemia
- Hypermagnesemia
- Cardiopulmonary resuscitation
Recommended Doses and Formulations
The typical formulations used are calcium chloride (10%) at 5-10 mL or calcium gluconate (10%) at 10-20 mL given intravenously, with the dose regimen often used for the administration of 10% calcium chloride being 10–20 mL (1–2 g) every 10–20 minutes or an infusion at 0.2–0.4 mL/kg/hr (0.02–0.04 g/kg/hr) 1.
Mechanism of Action and Precautions
Calcium works by enhancing myocardial contractility, vascular smooth muscle tone, and stabilizing cell membranes. However, calcium administration should be done cautiously in patients taking digoxin as it may potentiate digitalis toxicity. The onset of action is rapid, typically within minutes of administration, and the patient should be monitored for signs of hypercalcemia such as nausea, vomiting, and cardiac arrhythmias.
Key Considerations
- Calcium should be given through a large vein or central line to prevent tissue damage from extravasation.
- The patient's clinical condition and response to treatment should be closely monitored.
- High-dose insulin may also be considered in cases of calcium channel blocker overdose, as it has been shown to improve contractility, blood pressure, and survival in observational studies and case series 1.
From the Research
Hypocalcemia and Hypotension
- Hypocalcemia is a cause of refractory hypotension and heart failure, as illustrated by a case study where a patient's left ventricular function and blood pressure improved dramatically after intravenous calcium administration 2.
- Calcium channel blocker overdoses can lead to hypotension, and treatment may involve calcium administration to counteract the effects of the overdose 3.
- Hypocalcemia can occur in conjunction with multiple disorders and can be life-threatening if severe, with symptoms including neuromuscular irritability, tetany, and seizures, which can be rapidly resolved with intravenous administration of calcium gluconate 4.
Calcium Administration in Hypotension
- Calcium is vital for life, and extracellular calcium concentrations must be maintained within a precise concentration range, with low serum calcium (hypocalcemia) occurring in conjunction with multiple disorders 4.
- A study found that hypocalcemia with a serum ionized calcium <1.02 mmol/l was associated with a higher risk of severe hypotension during continuous renal replacement therapy (CRRT) 5.
- Calcium channel blockers, which dilate arteries by reducing calcium flux into cells, can effectively lower blood pressure, especially in combination with other drugs 6.
Treatment of Hypocalcemia-Induced Hypotension
- Treatment and management options for chronic hypocalcemia vary depending on the underlying disorder, with calcium and vitamin D supplementation often used to manage hypoparathyroidism 4.
- In cases of calcium channel blocker overdose, treatment may involve calcium administration, as well as other supportive measures such as atropine and intravenous fluids 3.
- Further studies are needed to assess whether treatment targets for serum calcium can improve the risk of hypotension during CRRT 5.