一位第四期慢性腎臟病 (CKD) 病人的血清鉀離子濃度為 6.8 mEq/L。護理師應優先執行哪項處置？

This question tests the priority of emergency nursing care for hyperkalemia. When serum potassium reaches 6.8 mEq/L, this is a medical emergency, because hyperkalemia directly interferes with the depolarization and repolarization of cardiac muscle cells, leading to fatal arrhythmias (such as ventricular fibrillation or cardiac arrest). According to nursing priority principles, safety comes first. Before implementing any potassium-lowering treatment (such as medications), physiological monitoring must first be established. Option B (placing a cardiac monitor) allows the nurse to immediately detect ECG changes such as peaked T waves, prolonged PR interval, or widened QRS. Option D (Kayexalate) can lower potassium but acts slowly (hours to days) and is not suitable for emergency management; option A is unrelated to the current crisis; option C is a preventive measure rather than treatment. In NCLEX reasoning, when a patient faces a potentially fatal arrhythmia, 'assessing and monitoring' cardiac status is the first step in action, followed by preparing to administer calcium gluconate to stabilize the cardiac cell membrane.