TCRN Practice Exam 2025 – Complete Prep for Your Test

In cases of hyperkalemia accompanied by ECG changes, such as a widened QRS complex, the initial treatment focuses on stabilizing the heart muscle's excitability and reducing the risk of serious arrhythmias. Calcium is the preferred agent in this scenario, as it helps to protect the myocardium from the effects of elevated potassium levels on cardiac conduction.

When potassium levels rise significantly, they can lead to disturbances in cardiac rhythm and conduction, notably by interfering with the normal action potential of cardiac cells. Calcium administration counteracts these effects, helping to restore the cardiac membrane potential and stabilize cardiac function. This is crucial in preventing potentially life-threatening arrhythmias associated with hyperkalemia.

Magnesium, while beneficial in certain contexts like torsades de pointes, does not have the same immediate effect on mitigating the cardiovascular consequences of hyperkalemia. Insulin is also effective in lowering serum potassium levels, but it acts more slowly and is not the initial treatment for immediate cardiac protection. Propranolol can manage the heart rate and myocardial oxygen demand but does not directly address the acute dangers posed by hyperkalemia.

Given the urgency of addressing a widened QRS due to hyperkalemia, calcium administration serves as a swift and effective means to safeguard cardiac function.