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) disrupts cardiac membrane potentials, increasing the risk of arrhythmias like ventricular tachycardia. Assessing pulse rate and rhythm first detects life-threatening cardiac changes, allowing prompt intervention (e.g., calcium gluconate) to stabilize the heart, preventing sudden cardiac arrest in this critical electrolyte imbalance. Choice B reason: Deep tendon reflexes are affected in severe hyperkalemia, causing weakness or hyporeflexia due to altered neuromuscular excitability. However, cardiac arrhythmias are a more immediate threat, as hyperkalemia’s primary danger is its effect on cardiac conduction, making reflex assessment secondary to pulse evaluation. Choice C reason: Respiratory rate and depth are not directly affected by hyperkalemia, as it primarily impacts cardiac and neuromuscular function. While severe cases may cause muscle weakness affecting breathing, cardiac arrhythmias pose a more immediate risk, making pulse assessment the priority to prevent sudden cardiac events. Choice D reason: Oxygen saturation is not directly altered by hyperkalemia, which affects potassium channels in cardiac and muscle cells, not pulmonary function. While hypoxia could exacerbate complications, the primary concern is cardiac arrhythmias, making pulse rate and rhythm assessment the first priority to ensure patient safety.