Hyperkalemia

A potassium of 6.8 mEq/L with peaked T waves means the heart could stop in minutes. The treatment sequence you choose — and the order you choose it in — determines whether it does.

Emergent hyperkalemia management follows three priorities in a specific order: stabilize the heart, shift potassium intracellularly, then remove potassium from the body. First, IV calcium gluconate (or calcium chloride via central line) is given to stabilize the cardiac membrane — it does NOT lower potassium but buys time by raising the threshold for cardiac depolarization. Effect is immediate (1-3 minutes) and lasts 30-60 minutes. Second, potassium is shifted into cells using regular insulin (typically 10 units IV) co-administered with dextrose (D50) to prevent hypoglycemia, and/or nebulized albuterol. Insulin-dextrose onset is 15-30 minutes, lasting 2-6 hours. Sodium bicarbonate may be used if acidosis is present since correcting pH drives potassium intracellularly. Third, potassium is eliminated via sodium polystyrene sulfonate (Kayexalate) orally or rectally, loop diuretics if renal function allows, or emergent hemodialysis for refractory cases. Nursing priorities include continuous cardiac monitoring, checking blood glucose every 1-2 hours after insulin administration, and monitoring for rebound hyperkalemia as shifting agents wear off.

Key Distinctions

Calcium gluconate protects the heart but does NOT lower potassium — students frequently select it as a potassium-lowering intervention. Insulin shifts potassium into cells (temporary fix) while Kayexalate removes it from the body (actual elimination) — these are different mechanisms with different timelines. Regular insulin is used, never rapid-acting analogs like lispro, for this IV protocol.

Clinical Pearl

Think C-S-E: Cardiac stabilization first (calcium), Shift second (insulin + glucose), Eliminate last (Kayexalate, dialysis). Calcium buys time, insulin buys hours, elimination solves the problem.

Recognition

Normal serum potassium is 3.5-5.0 mEq/L. Hyperkalemia (>5.0 mEq/L) most commonly results from renal failure (decreased excretion), potassium-sparing diuretics, ACE inhibitors/ARBs, massive tissue destruction (burns, crush injuries), and metabolic acidosis (hydrogen ions shift into cells, potassium shifts out).

The cardiac effects follow a predictable ECG progression: first peaked T waves, then widened QRS complex, then flattened P waves, and finally a sine wave pattern preceding cardiac arrest. The earliest ECG change — peaked T waves — is a critical NCLEX recognition point.

Treatment follows three principles: stabilize the cardiac membrane (IV calcium gluconate), shift potassium into cells (insulin + glucose, sodium bicarbonate, albuterol), and remove potassium from the body (kayexalate, dialysis, loop diuretics).

Key Distinctions

Don't confuse hyperkalemia with hypokalemia symptoms. Hyperkalemia causes muscle weakness that can progress to flaccid paralysis, while hypokalemia also causes weakness but with additional cramping, decreased bowel sounds (paralytic ileus), and U waves on ECG.

Calcium gluconate does NOT lower potassium — it stabilizes the cardiac membrane to prevent fatal dysrhythmias while you use other interventions to actually lower the level. This is a common misconception tested on NCLEX.

Clinical Pearl

IV calcium gluconate is always the FIRST intervention in severe hyperkalemia with ECG changes — it acts within minutes to stabilize the heart. Then give insulin with glucose (insulin drives potassium into cells; glucose prevents hypoglycemia). Remember the mnemonic for hyperkalemia signs: "MURDER" — Muscle weakness, Urine output changes, Respiratory distress, Decreased cardiac contractility, ECG changes, Reflexes decreased.