Introduction to Clinical Pharmacology Chapter 38- Cardiotonics and Inotropic Drugs

1. Introduction to Clinical PharmacologyChapter 38-Cardiotonics and Inotropic Drugs

2. Heart Failure • Most common symptoms associated with HF include: • Left ventricular dysfunction • Shortness of breath with exercise • dry hacking cough or wheezing • orthopnea, restlessness, edema • Left ventricular dysfunction • Pulmonary symptoms-dyspnea, moist cough with production of frothy, pink sputum • EF less than 40%, heart is enlarged and dilated • Right ventricular dysfunction • Peripheral edema, wt. gain

3. Cardiotonics: Actions and Uses • Actions: • Increase cardiac output through positive inotropic activity; they slow the conduction velocity through the atrioventricular (AV) node in the heart and decrease the heart rate through a negative chronotropic effect • Uses: • Used to treat: Heart failure; atrial fibrillation • Patients with persistent symptoms, recurrent hospitalizations, or as indicated in conjunction with ACE inhibitors, loop diuretics and B blockers

4. Cardiotonics: Adverse Reactions • Central nervous system reaction: • Headache; weakness; drowsiness; visual disturbance • Cardiovascular and gastrointestinal reactions: • Arrhythmias; gastrointestinal upset; anorexia

5. Cardiotonics: Contraindications and Precautions • Contraindicated: In the presence of digitalis toxicity and in patients with known hypersensitivity, ventricular failure, ventricular tachycardia, cardiac tamponade or AV block • Precautions: Patients with electrolyte imbalance, severe carditis, heart block, myocardial infarction, severe pulmonary disease, acute glomerulonephritis, impaired renal or hepatic function • Digoxin and digoxin immune fab used cautiously during pregnancy and lactation, when the potential benefit outweighs the potential harm to the fetus

6. Cardiotonics: Interactions

7. Miscellaneous Inotropic Drugs • Inamrinone and milrinone: have inotropic actions and are used in the short-term management of severe HF that is not controlled by the digitalis preparations • Nurse must continuously monitor the patient’s heart rate and blood pressure with administration of either drug • If hypotension occurs, the drug is discontinued or the rate of administration is reduced • Continuous cardiac monitoring is necessary because life-threatening arrhythmias may occur

8. Nursing Process: Assessment • Preadministration assessment: • The physical assessment should include: • Taking blood pressure, apical-radial pulse rate, respiratory rate • Auscultating the lungs, noting any unusual sounds during inspiration and expiration • Examining the extremities for edema • Checking the jugular veins for distention • Measuring weight

9. Nursing Process: Assessment • Preadministration assessment: (cont’d) • Inspecting sputum raised (if any), and noting the appearance (e.g., frothy, pink-tinged, clear, yellow) • Looking for evidence of other problems, such as cyanosis, shortness of breath on exertion (if the patient is allowed out of bed) or when lying flat, and mental changes • The primary care provider also may order laboratory and diagnostic tests

10. Nursing Process: Assessment • Preadministration assessment: (cont’d) • Because digoxin reacts with many medications, the nurse must take a careful drug history • Before administering each dose of a cardiotonic, the nurse takes the apical pulse rate for 60 seconds, records it in the designated area on the chart or the medication administration record • Pulse rate below 60bpm and above 100bpm in adults: withhold the drug and inform the primary health care provider, PEDS-notify PCP if AP <70 bpm or below 90 bpm in infant

11. Nursing Process: Assessment • Ongoing assessment: (con’td) • Weighs patients receiving a cardiotonic drug daily, or as ordered • I and O, especially in the presence of edema or HF • Assess the patient for peripheral edema and auscultates the lungs for rales or crackles throughout therapy

12. Nursing Process: Planning • The expected outcomes of the patient depend on the specific reason for administering the drug, but may include: • Optimal response to therapy • Support of patient needs related to the management of adverse reactions • Understanding of and compliance with the prescribed drug regimen

13. Nursing Process: Implementation • Promoting an optimal response to therapy • The nurse should carefully check the primary care provider’s order and the drug container • Digitalization • Maybe accomplished by two general methods: Rapid digitalization and gradual digitalization • Involves giving a series of doses until the drug begins to exert a full therapeutic effect, additional freactions of the digitalis dose are administered at 6-8 hour intervals

14. Nursing Process: Implementation • Promoting an optimal response to therapy (cont’d) • Digitalization (cont’d) • During digitalization, the nurse takes the blood pressure, pulse, and respiratory rate every 2 to 4 hours or as ordered by the primary care provider • Periodic electrocardiograms, serum electrolytes, hepatic and renal function tests, and other laboratory studies also may be ordered

15. Nursing Alert • Plasma digoxin levels are monitored closely • Plasma levels should be drawn immediately before the next dose or 6-8 hours after the last dose regardless of route • Plasma dig. Levels greater than 2 nanograms/ml are toxic are must be reported to PCP • Hypokalemia makes heart muscle more sensitive to digitalis, increasing the possibility of developing digitalis toxicity

16. Nursing Process: Implementation • Promoting an optimal response to therapy (cont’d) • Parenteral administration: • The nurse may give a cardiotonic orally, IV, or intramuscularly (IM) • When a cardiotonic drug is given IV, it is administered slowly and the administration site is assessed for redness or infiltration • When giving a cardiotonic drug IM, the nurse should rotate the injection sites

17. Nursing Process: Implementation • Promoting an optimal response to therapy (cont’d) • Oral Administration: • Nurse can administer oral preparations without regard to meals • Monitoring and managing patient needs • Risk of imbalanced nutrition: Less than body requires • Observe the patient for adverse reactions, such as anorexia, vomiting, nausea (symptoms of toxicity)

18. Nursing Process: Implementation • Monitoring and managing patient needs (con’td) • Potential complication: Digital toxicity • Observe for signs of digitalis toxicity- 2-4 hours during digitalization and 1-2 times a day • Digoxin toxicity can be successfully treated by simply withdrawing the drug; severe life-threatening toxicity is treated with digoxin immune fab • Nurse should be alert for the possibility of worsening HF, low cardiac output, hypokalemia, or atrial fibrillation • Give atropine if bradycardia develops!!

19. Nursing Process: Implementation • Educating the patient and family: • If HR falls below 60 bpm in adult, 70 bpm in child-instruct them to call PCP • The patient and family must understand that the prescribed drug must be taken exactly as directed by the primary care provider-do not miss or double a dose • Show the patient or a family member the correct technique for taking the pulse

20. Nursing Process: Evaluation • The therapeutic effect is achieved • The patient maintains an adequate nutritional status • The patient is able to carry out activities of daily living • Adverse reactions are identified, reported to the primary care provider, and managed using appropriate nursing interventions • The patient verbalizes the importance of continued follow-up care

21. Nursing Process: Evaluation (cont’d) • The patient verbalizes the importance of complying with the prescribed therapeutic regimen • The patient and family demonstrate an understanding of the drug regimen • The patient complies with the prescribed drug regimen