Chapter 22- Cardiac Glycosides- digoxin

who is at risk for dig toxicity?

-cardiac pacemaker -hypokalemia -dysrhythmias -V-fib -hypercalcemia -hepatic, renal dysfunction -AV block -hypothyroidism or renal disease -advanced age- decreased renal function -licorice may increase K+ levels and lead to dig toxicity and St. John's Wort may reduce dig levels

nursing implications

-assess history, drug allergies, contraindication -assess clinical parameters, including: --BP --apical pulse for 1 full minute (hold digoxin if pulse if 60 bpm for adults) --heart sounds, breath sounds --weight, I&O measures --ECG --labs: potassium, renal, and liver function studies

cardiac glycosides- adverse effects

-digoxin ----very narrow therapeutic window ----drug levels must be monitored- 0.5-2 mg/mL (therapeutic drug level) ----low potassium levels increase its toxicity ----electrolyte levels must be monitored ----cardiovascular: dysrhythmias, including bradycardia or tachycardia ----CNS: headaches, fatigue, malaise, confusion, convulsions ----eye: colored vision (seeing green, yellow, purple dots), halo vision, flickering lights ----GI anorexia, nausea, vomiting, diarrhea (last three common- check levels for toxicity- do not repeat dose if it is thrown up) -teach your patients to identify all the signs of toxicity and medication interactions

digoxin toxicity antidote

-digoxin immune Fab (digibind) given if: ---life-threatening cardiac dysrhythmias ---life-threatening digoxin overdose ---one vial binds 0.5 mg of digoxin ---dig levels will still be elevated for days to weeks after administration ---use clinical s/s, not just dig levels for monitoring

digoxin is effective if:

-increased urinary output -decreased edema, shortness of breath, dyspnea, crackles, and fatigue -resolution of paroxysmal nocturnal dyspnea -improved peripheral pulses, skin color, temperature monitor for adverse effects

medication/ food interactions

-maintain K+ levels 3.5-5 -caution with thiazide diuretics (HTZ), loop diuretics (furosemide)- may lead to hypokalemia -caution with ACE inhibitors (-pril drugs), and some ARBS (losartan) may lead to hyperkalemia -foods high in potassium (K+): ex. green leafy vegetables, bananas, potatoes -caution with verapamil (calcium channel blocker)- increases plasma digoxin levels -quinidine increases the risk of digoxin toxicity- avoid concurrent usage

cardiac glycosides

-originally obtained from digitalis plant- foxglove -used to treat: heart failure, used to control ventricular response to atrial fibrillation or flutter contraindicated in abnormal ventricular rhythms- VT, VF -increased force and velocity of myocardial contraction, so increases cardiac contractility (without an increase in oxygen consumption) -reduced heart rate -decreased automaticity at SA node, decreased AV nodal conduction -"slows and strengthens the heart"

teaching

-take med at same time everyday -if dose missed, don't double next dose -notify PCP if pulse is: <60/min in adults, <70/min in children, <90/min in infants (less than 12 months old) -instruct patients to observe symptoms of hypokalemia and hyperkalemia and notify PCP. -before giving any dose of digoxin, count apical pulse for 1 full minute -for apical pulse less than 60 or greater than 100 beats/ minute: hold dose, notify prescriber- what would you do if N/V? report to provider, repeat dose? no -hold dose and notify prescriber if patient experiences signs/symptoms of toxicity ----anorexia, nausea, vomiting, abdominal pain ----visual disturbances (blurred vision, seeing green or yellow halos around objects) -check dosage forms carefully, and follow instructions for giving -avoid giving digoxin with high-fiber foods (fiber binds with digitalis causing decreased absorption)- ex: raisin bran -avoid giving digoxin with antacids (antacids bind with digitalis causing decreased absorption)- ex: tums -patients should immediately report a weight gain of 2 or more pounds in 1 day or 5 or more pounds in 1 week

digoxin toxicity interventions

1. DC drug 2. continuous EKG monitoring 3. get dig and electrolyte levels 4. give K supplements for hypokalemia as ordered- if hyperkalemia >5.0 mEq/L hold K+- treat dysrhythmias with phenytoin or lidocaine, treat bradycardia with atropine, for excessive overdose, activated charcoal, cholestyramine, or digibind 5. supportive tx for GI sx 6. give antidote