Intravenous injection of calcium gluconate is a core emergency measure for rapidly correcting hypocalcemia and relieving life-threatening symptoms in acute hypocalcemia episodes. It can increase blood calcium levels within minutes, quickly resolving critical symptoms such as muscle spasms and arrhythmias, and buys time for subsequent etiological treatment. It is a standard protocol in clinical emergency care.

I. Core Emergency Value: Rapid Onset to Resolve Critical Symptoms

Acute hypocalcemia (usually blood calcium < 1.75 mmol/L) causes abnormally increased neuromuscular excitability and cardiovascular dysfunction due to a sudden drop in calcium ion concentration. Without timely intervention, it may lead to laryngospasm or cardiac arrest. Intravenous calcium gluconate exerts three key emergency effects through "direct calcium ion supplementation and rapid onset":

1. Rapid Relief of Neuromuscular Spasms

Hypocalcemia disrupts the membrane potential of nerve cells, triggering tonic muscle contractions, which manifest as hand-foot spasms, facial muscle spasms, and laryngospasm (characterized by dyspnea and stridor). After intravenous injection of calcium gluconate, calcium ions enter the bloodstream within 3–5 minutes, correcting extracellular hypocalcemia and reducing neuromuscular excitability. Spasms and convulsions are quickly relieved—life-threatening symptoms like laryngospasm usually improve significantly within 10 minutes, avoiding the risk of asphyxiation.

2. Correction of Arrhythmias and Circulatory Stabilization

Calcium ions are critical for excitation-contraction coupling in cardiomyocytes. Acute hypocalcemia causes abnormal myocardial conduction, leading to ventricular premature beats, ventricular tachycardia, or even ventricular fibrillation. Intravenous calcium gluconate directly supplements calcium ions required by cardiomyocytes, improving the electrophysiological stability of the heart. Arrhythmias can be relieved within 5–10 minutes, and heart rate and rhythm return to normal, preventing circulatory failure.

3. Buying Time for Etiological Treatment

The core goal of intravenous calcium gluconate is "emergency symptomatic management." After quickly controlling critical symptoms, doctors can further investigate the cause of hypocalcemia (e.g., hypoparathyroidism, vitamin D deficiency, renal failure) and develop long-term treatment plans (e.g., oral calcium supplements, vitamin D supplementation) to prevent symptom recurrence.

II. Emergency Mechanism: Direct Supplementation + Cellular Function Stabilization

The emergency mechanism of intravenous calcium gluconate centers on "rapidly increasing blood calcium levels and restoring cellular physiological functions," which occurs in two specific steps:

1. Direct Calcium Ion Supplementation to Rapidly Raise Blood Calcium

After intravenous injection, calcium gluconate dissociates rapidly into calcium ions (Ca²⁺), which directly enter the extracellular fluid. This increases blood calcium levels from a critical range (e.g., 1.5 mmol/L) to a safe range (2.0–2.25 mmol/L) within minutes, quickly correcting the core pathological state of "hypocalcemia."

2. Restoration of Nerve and Cardiomyocyte Function

For nerve cells: Calcium ions stabilize the nerve cell membrane, reducing its permeability to sodium ions and decreasing abnormal nerve impulse firing, thereby relieving muscle spasms.

For cardiomyocytes: After entering cardiomyocytes, calcium ions bind to troponin to initiate myocardial contraction. Meanwhile, they repair the electrical activity of the myocardial conduction system, preventing conduction block and malignant arrhythmias.

III. Clinical Emergency Protocol: Strict Control of Dosage and Infusion Rate

Emergency treatment of acute hypocalcemia must strictly follow the principles of "precise dosage and slow injection" to avoid adverse reactions caused by improper medication. The specific protocol is as follows:

1. Common Dosages

Adults: A single intravenous injection of 10–20 mL of 10% calcium gluconate injection (containing 90–180 mg of elemental calcium). If symptoms persist, a second injection can be repeated after 15–30 minutes. The total dosage within 24 hours should not exceed 50 mL (containing 450 mg of elemental calcium).

Children: Dosage is calculated by body weight—0.5–1 mL/kg of 10% calcium gluconate injection per single dose, with a maximum single dose not exceeding 20 mL. The injection must be administered slowly (duration > 10 minutes) to avoid hypercalcemia caused by excessive dosage.

2. Infusion Rate Control

Intravenous injection must be slow: the rate should be ≤ 2 mL/min for adults and ≤ 1 mL/min for children. Rapid bolus injection is strictly prohibited—sudden increases in blood calcium levels due to rapid injection can cause hypercalcemia, which may lead to arrhythmias (e.g., bradycardia), a sharp drop in blood pressure, or even cardiac arrest.

3. Adaptation of Administration Route

Critical symptoms (e.g., laryngospasm, severe arrhythmia): "Intravenous push" is used to ensure rapid drug onset.

Persistent symptoms or need for blood calcium maintenance: 20–30 mL of 10% calcium gluconate injection can be added to 250–500 mL of 5% glucose injection for slow intravenous infusion (infusion rate: 1–2 mL/min), maintaining stable blood calcium levels for 4–6 hours.

IV. Emergency Precautions: Risk Avoidance to Ensure Safety

Although intravenous calcium gluconate is a key emergency measure, operational standards and risk prevention must be emphasized to avoid adverse reactions:

1. Monitoring Vital Signs and Blood Calcium

Vital signs (heart rate, rhythm, blood pressure) must be continuously monitored during injection. If bradycardia (adult heart rate < 50 beats/min) or hypotension occurs, injection should be stopped immediately. Blood calcium should be rechecked within 2 hours after injection to avoid hypercalcemia (> 2.75 mmol/L), which may cause kidney damage or constipation.

2. Avoiding Drug Extravasation

Calcium gluconate solution is highly irritating to blood vessels. Extravasation into subcutaneous tissue during injection can cause local tissue necrosis and calcification. A large, straight vein (e.g., median cubital vein) should be selected. During injection, observe for local swelling or pain—if extravasation occurs, stop injection immediately and apply wet compresses with 50% magnesium sulfate solution.

3. Contraindications and Drug Interactions

Contraindicated populations: Patients with hypercalcemia or kidney stones (calcium-containing stones) are prohibited from using it.

Drug interactions: Concurrent use with cardiac glycosides (e.g., digoxin) should be avoided. Calcium ions enhance the myocardial toxicity of cardiac glycosides, which may lead to severe arrhythmias. An interval of more than 4 hours is required between administrations.

Intravenous calcium gluconate has irreplaceable value in the emergency treatment of acute hypocalcemia. By rapidly supplementing calcium ions, it relieves critical symptoms such as muscle spasms and arrhythmias within minutes, buying crucial time for etiological treatment. In clinical practice, strict control of dosage and injection rate, along with monitoring of vital signs and blood calcium, is essential to avoid adverse reactions and ensure safe and effective emergency care.