Transcript Roach: Introductory Clinical Pharmacology

Introduction to Clinical
Pharmacology
Chapter 38Cardiotonics and Inotropic Drugs
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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
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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
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Cardiotonics: Adverse Reactions
• Central nervous system reaction:
– Headache; weakness; drowsiness; visual
disturbance
• Cardiovascular and gastrointestinal
reactions:
– Arrhythmias; gastrointestinal upset;
anorexia
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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
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Cardiotonics: Interactions
Interactant drug
Amiodarone
Benzodiazepines
Indomethacin
Itraconazole
Macrolides
Propafenone
Quinidine
Spironolactone
Tetracyclines
Verapamil
Effect of interaction
Increased plasma
digitalis levels leading to
toxicity
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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)
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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 lifethreatening 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!!
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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
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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
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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
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