A client is prescribed digoxin (Lanoxin) for heart failure. What should the nurse assess BEFORE administering each dose?

DIGOXIN (Lanoxin) is a CARDIAC GLYCOSIDE used for: heart failure (positive inotrope — increases cardiac contractility); atrial fibrillation/flutter (rate control — increases AV node refractory period, slowing ventricular rate). MECHANISM: inhibits Na-K-ATPase pump → increased intracellular sodium → increased intracellular calcium → stronger cardiac contraction; also has vagotonic effects (slows SA and AV node). BEFORE EACH DOSE: APICAL PULSE FOR ONE FULL MINUTE — if below 60 bpm (bradycardia) in adults, HOLD THE DOSE and notify provider; per some protocols the parameter may be 50 or 55; in children the parameters vary by age. THERAPEUTIC RANGE: 0.5-2.0 ng/mL (the therapeutic range is narrow — easy to reach toxic levels). DIGOXIN TOXICITY SIGNS (EARLY): GI — anorexia, nausea, vomiting, diarrhea; NEUROLOGICAL — headache, fatigue, visual changes (classic: YELLOW-GREEN HALOS around lights, blurred vision, xanthopsia); CARDIAC — bradycardia, heart block, dysrhythmias (the most dangerous aspect — almost any dysrhythmia possible). FACTORS THAT INCREASE TOXICITY RISK: hypokalemia (low K+ makes the heart more sensitive to digoxin — monitor K+ levels, particularly in patients taking diuretics); hypomagnesemia; hypercalcemia; renal insufficiency (digoxin renally cleared); old age; drug interactions (amiodarone, verapamil, quinidine elevate digoxin levels). TREATMENT OF TOXICITY: DIGOXIN IMMUNE FAB (Digibind) — specific antidote; correct electrolytes; cardiac monitoring; supportive care. PN RESPONSIBILITIES: check apical rate before each dose; hold for bradycardia per parameters; report signs of toxicity immediately; monitor K+ levels; teach client to report nausea, vision changes, or slow pulse.