In reviewing the electrolytes of a patient, the nurse notes the serum potassium level has increased from 4.6 mEq/L to 6.1 mEq/L. Which assessment does the nurse perform first to prevent harm?

Choice A reason: Hyperkalemia (6.1 mEq/L) alters cardiac membrane potentials, risking arrhythmias like ventricular fibrillation. Assessing pulse rate and rhythm first identifies irregular rhythms, enabling urgent interventions (e.g., calcium gluconate) to stabilize cardiac conduction, preventing sudden death, as the heart is most vulnerable to potassium imbalances. Choice B reason: Hyperkalemia may reduce deep tendon reflexes by impairing neuromuscular excitability, causing weakness. However, this is less urgent than cardiac effects, as arrhythmias are life-threatening. Reflex assessment follows cardiac evaluation, as hyperkalemia’s primary danger is its impact on heart rhythm, not neurological function. Choice C reason: Respiratory rate and depth are unaffected by hyperkalemia unless severe muscle weakness occurs, which is rare at 6.1 mEq/L. Cardiac arrhythmias are the primary concern, as elevated potassium disrupts cardiac conduction, making pulse assessment critical to prevent sudden cardiac events over respiratory monitoring. Choice D reason: Oxygen saturation is not directly impacted by hyperkalemia, which primarily affects cardiac and neuromuscular function. While hypoxia could worsen outcomes, the immediate risk is arrhythmias, making pulse rate and rhythm the priority assessment to detect and address life-threatening cardiac changes promptly.