Emergency Nursing Orientation 3.0 Cardiovascular Emergencies Practice Exam

Elevated potassium levels change the heart’s electrical stability and make dangerous rhythms much more likely. Potassium sits outside heart cells to help set the resting membrane potential; when it’s too high, the resting potential becomes less negative, sodium channels don’t recover promptly, conduction slows, and the ECG can show peaked T waves, widening QRS, and eventually dangerous rhythms like ventricular fibrillation. The priority is to stabilize the heart while reducing the potassium load. Calcium is given first to stabilize the myocardial membranes, buying time for other measures. Then insulin with glucose is used to move potassium back into cells, lowering the serum level quickly. If acidosis is present, bicarbonate helps by promoting cellular potassium shift and correcting the pH. Additional therapies such as beta-agonists, diuretics, or dialysis may be used depending on the situation and renal function. This approach aligns with treating hyperkalemia and its correction with calcium, insulin plus glucose, and bicarbonate. While hypocalcemia would require calcium, and hypernatremia or fluid restriction do not address the dangerous potassium surplus, and hypokalemia would require potassium replacement, these do not fit the scenario of an arrhythmia-predisposing hyperkalemia.