What is the nurse's priority action for a client with low potassium scheduled to receive furosemide?

For a client with low potassium levels, the nurse's priority action when the patient is scheduled to receive furosemide is to hold the medication. Furosemide, a loop diuretic, is known to promote renal excretion of potassium, which could exacerbate the already low potassium levels, increasing the risk of serious complications such as cardiac arrhythmias.

When potassium levels drop, the heart's electrical activity can be significantly affected, leading to potentially life-threatening conditions. Therefore, holding furosemide helps prevent further lowering of potassium and allows time to address the electrolyte imbalance safely.

While other actions, such as notifying the healthcare provider or obtaining an ECG, may also be appropriate in a broader context, the most immediate and critical action in this situation is to withhold the furosemide to protect the patient's safety.