A nurse is caring for a patient with acute kidney injury (AKI) who has developed severe hyperkalemia (K+ 7.2 mEq/L). The patient is experiencing cardiac arrhythmias. What is the nurse's priority intervention?

IV calcium gluconate is the priority for immediate cardiac membrane stabilization in severe hyperkalemia with arrhythmias. Other options address potassium removal but do not provide immediate cardiac protection.

Clinical Priority Setting in Hyperkalemic Emergency

The correct answer is Administer IV calcium gluconate as prescribed. In the context of a patient with acute kidney injury (AKI) presenting with severe hyperkalemia (K+ 7.2 mEq/L) and active cardiac arrhythmias, the immediate priority is to stabilize the myocardial cell membrane to prevent life-threatening cardiac arrest.

Pathophysiology and Mechanism of Action
The primary danger of severe hyperkalemia is its effect on the electrical conduction system of the heart. Elevated extracellular potassium alters the resting membrane potential of cardiac myocytes. Initially, this makes the cells more excitable, but as potassium levels continue to rise, the resting potential becomes less negative, inactivating sodium channels and slowing impulse conduction. This manifests on an ECG as peaked T-waves, loss of P-waves, widened QRS complexes, and eventually a sine-wave pattern that deteriorates into ventricular fibrillation or asystole ^[1]. The cardiac arrhythmias present in this patient indicate that this destabilization is already occurring. Intravenous calcium gluconate works immediately by antagonizing the effect of potassium on the myocardial cell membrane, raising the threshold potential and restoring a normal gradient between the resting and threshold potentials. This does not lower the serum potassium level, but it directly counteracts the cardiotoxic effects, making it the only intervention that provides immediate cardioprotection ^[2].

Why Other Options Are Not the Priority
While the other interventions are essential components of hyperkalemia management, they do not provide the immediate cardiac stabilization required in an emergency.

- Emergency hemodialysis is the most effective method for removing potassium from the body, especially in a patient with AKI whose kidneys are non-functional. However, even in an emergency, setting up dialysis takes time. During that preparation time, the patient’s unstable myocardium is vulnerable to fatal arrhythmias. Calcium must be administered first to protect the heart while dialysis arrangements are made ^[2].
- Sodium polystyrene sulfonate (Kayexalate) is a cation-exchange resin that removes potassium through the gastrointestinal tract. Its onset of action is slow, taking hours to significantly lower serum potassium levels. It has no role in the acute, minute-to-minute management of a life-threatening arrhythmia ^[2].
- Restricting potassium intake and monitoring cardiac rhythm is a fundamental nursing action for preventing worsening hyperkalemia, but it is not a treatment for an existing crisis. Continuous cardiac monitoring is crucial during and after the administration of calcium and other therapies, but it is a supportive measure, not the priority intervention to stop the immediate threat.

Clinical Practice Integration
For a patient with severe hyperkalemia and ECG changes or arrhythmias, the clinical sequence is clear. The nurse must first recognize that the arrhythmia represents an immediate threat of cardiac arrest. The priority action is to administer IV calcium gluconate or calcium chloride as prescribed to rapidly stabilize the cardiac membrane, an intervention supported by clinical guidelines for managing hyperkalemic emergencies ^[2]. Following this, therapies to shift potassium intracellularly (such as IV insulin and glucose) and to eliminate potassium from the body (such as hemodialysis) can be initiated. This case highlights the critical distinction between treatments that are temporizing and cardioprotective versus those that are definitive and potassium-lowering.