Medicine
Management of hyperkalemia in the emergency department
Quick fact
In severe hyperkalemia, giving intravenous calcium can reverse life-threatening ECG changes within minutes, but it does not lower potassium levels—it only protects the heart temporarily.
Why this is interesting
A patient with kidney failure arrives with a dangerously high potassium level—one that could stop their heart at any moment. How do emergency doctors buy time and save the day?
Read the full explanation
Understanding Management of hyperkalemia in the emergency department
Potassium is an electrolyte that helps nerves and muscles, especially the heart, function normally. Normally, the kidneys filter out excess potassium, and hormones like insulin and adrenaline help move it into cells. In hyperkalemia, the balance is disrupted—either because the kidneys can't excrete enough or because potassium leaks from damaged cells. This excess potassium in the blood disrupts the electrical activity of the heart, which can lead to dangerous arrhythmias. The emergency treatment follows three steps: first, protect the heart with calcium, which stabilizes the heart cells' electrical activity. Second, shift potassium into cells using insulin plus glucose (to prevent low blood sugar) and sometimes inhaled beta-agonists like albuterol. Third, remove potassium from the body using medications like diuretics, binding agents like sodium polystyrene sulfonate, or dialysis for severe cases. These steps are done in order, but the first two are temporary fixes—the body's total potassium isn't reduced until removal happens.
A deeper explanation
Hyperkalemia affects the heart because potassium changes the resting membrane potential of cardiac myocytes. As extracellular potassium rises, the resting potential becomes less negative, leading to increased excitability and then slowed conduction, which manifests as characteristic ECG changes such as peaking T waves, widened QRS, and eventually a sine wave pattern or cardiac arrest. Calcium acts as a direct antagonist, stabilizing the cardiac cell membrane by reducing the effect of hyperkalemia on the resting potential, thereby protecting the heart while other measures take effect. Insulin shifts potassium into cells by stimulating the sodium-potassium ATPase pump, which moves potassium from the blood into cells; glucose is given with insulin to prevent hypoglycemia. Beta-agonists also activate the same pump, further promoting intracellular uptake. These methods are rapid but temporary. Definitive treatment requires removing potassium from the body, either through the kidneys (using diuretics) or the gastrointestinal tract (using binding agents), or via dialysis in severe cases. The urgency of each step depends on the ECG changes and the absolute potassium level, with thresholds guiding the decision to start with calcium and emergent dialysis. This three-phase approach is essential to prevent cardiac death while correcting the underlying imbalance.