A 76-year-old taking digoxin and a loop diuretic is observed after 3 days of poor intake. Creatinine rose from 0.9 to 1.8 mg/dL (reference 0.6-1.2); potassium is 3.1 mEq/L (3.5-5.0). A digoxin level drawn 10 hours after the last dose is 2.6 ng/mL (laboratory range 0.5-2.0). New nausea, yellow-tinted vision, and intermittent ventricular ectopy are present. The client is alert, BP is 116/70 mm Hg, and lungs are clear. Prescribed potassium replacement has begun, and the clinician is assessing the client. Select the most likely syndrome, TWO additional nursing actions now, and TWO parameters most directly tracking electrical risk during the next 4 hours.

Correct answer
Choose chronic digoxin toxicity; withhold digoxin and begin continuous ECG monitoring. Track serum potassium and ventricular rate/rhythm.

Why this is correct
Reduced renal clearance raises digoxin exposure, while low potassium increases myocardial sensitivity. The appropriately timed elevated level, visual changes, nausea, and ectopy form a coherent drug-toxicity pattern. Existing potassium replacement does not make another digoxin dose safe.

Clinical picture
A stable blood pressure does not exclude dangerous electrical effects. Escalation continues if perfusion deteriorates or a dangerous rhythm develops; this stable observation scenario does not imply that withholding medication alone treats severe poisoning.

Memory hook
Think exposure plus sensitivity: impaired clearance increases exposure; low potassium increases sensitivity. This is a causal reminder, not a formula that predicts the required antidote dose.

NCLEX decision rule
Integrate the dosing interval, kidney function, electrolyte status and rhythm before giving another narrow-therapeutic-index medicine. Monitor the immediate mechanism of harm while ordered corrective treatment proceeds.

Why the alternatives are wrong
Acute ischemia is not established by these findings and does not explain the digoxin level plus visual symptoms as well. Volume depletion contributes to impaired clearance but the phrase without drug toxicity contradicts the full pattern. Viral illness cannot explain the combined drug and electrical findings. Continuing diuresis based only on a heart-failure history could worsen potassium and volume depletion. An antiemetic can mask symptoms without reducing toxicity. The already appropriately timed level and clinical findings justify holding the dose without awaiting another level. Weight helps assess volume status; troponin evaluates myocardial injury, and hemoglobin helps evaluate anemia or concentration changes. None tracks the immediate drug-related electrical hazard as directly as potassium and ECG.