Monday, April 2, 2012

CARDIAC GLYCOSIDES AND INOTROPIC AGENTS



·         Inhibit sodium-potassium pump thus increasing intracellular calcium for more efficient contraction of cardiac muscle fibers
·         Action: positive inotropic (increased myocardial contraction , ↑ stroke volume), negative chronotropic (decreased heart rate), negative dromotropic action (decreased conduction of heart cells)
·         Indication:
o    CHF, atrial fibrillation, atrial flutter, atrial tachycardia
·         Contraindication:
o    Ventricular dysrhythmias, 2nd or 3rd degree heart block
·         Use with caution:
o     Acute MI, renal disease, hypothyroidism, hypokalemia

Example:
digoxin (Lanoxin®)
digitoxin (Crystodigin®)
milrinone (Primacor®)
amrinone (Inocor®)
nesiritide (Natrecor®)

Side Effects:

·         Bradycardia
·         Arrythmias
·         Headache
·         Nausea and vomiting
·         Hypotension
·         Abdominal pain
·         Visual disturbances


Digitalis Toxicity:

·         Anorexia
·         Diarrhea
·         Nausea and vomiting
·         Bradycardia
·         PVC
·         Cardiac dysrhythmias
·         Headaches
·         Malaise
·         Blurred vision
·         Visual illusions (white, green, yellow halos around objects)
·         Confusion and delirium

Nursing Considerations:

ü  Assess for signs and symptoms of toxicity.
ü  Check apical pulse rate before administering digoxin. Do not administer if HR is <60 bpm.
ü  Check for signs of peripheral and pulmonary edema.
ü  Check serum digoxin level.
o    Normal therapeutic range: 0.5 to 2.0 ng/ml
o    Maintenance dose: 0.125 to 0.5 mg/dl
o    Indicative of digitalis toxicity: >2.0 ng/ml
o    Antidote for digitalis toxicity: Digoxin immune Fab (Ovine®, Digibind®)
ü  Report if hypokalemia is present. Digitalis should be discontinued until serum potassium level is sufficient. 

ü  Provide patient teachings:
o    Teach patien about importance of compliance with drug therapy.
o    Check PR before administering drug.
o    Instruct to report side effects.
o    Advise patient to eat foods rich in potassium (fresh and dried fruits, fruit juices, vegetables, potatoes).




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