Calcium salts are recommended by many toxicologists for the first-line treatment of CCB overdose. As a guideline, calcium chloride should be initiated as a 10 to 20 mg/kg bolus injection. Calcium chloride may be preferable to gluconate preparations because it produces more reliable plasma ionized calcium concentrations. Calcium chloride is available in a 10-mL 10% solution, which may be diluted to 100 mL in normal saline and infused over 5 min via central venous catheter as a test bolus in adults. If this infusion improves heart rate or conduction on ECG or increases the arterial blood pressure, then a constant infusion at 20 to 50 mg/kg/h CaCl 2 should be initiated. As a general end point, ionized plasma calcium concentrations should be maintained between 2.0 and 3.0 meq/L. The elevated plasma calcium concentration improves cardiac conduction and contraction simply by increasing the driving force of the calcium ion's entry through L-type channels that are not closed. If the calcium channels are uniformly saturated by a CCB (in particular, verapamil), then the proportion of L-channels that are closed will be nearly 100 percent. In this situation, even the highest of plasma calcium concentrations will not improve cardiac function. Calcium infusion also may cause vomiting, acute rhythm disturbances including asystole, and local irritative effects that may result in serious sequelae, including upper extremity compartment syndromes.
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