Drug treatment for CHF Flashcards
What are the 6 mechanisms of low cardiac output?
1) Low preload
2) HR too slow
3) HR too fast
4) Diminished inotropic state (contractility)
5) Excessive vasoconstriction
6) Excessive or abnormal contractility
What is the treatment for low preload leading to low CO?
Crystalloid, blood
What is the treatment for bradycardia leading to low CO?
Atropine, isoproterenol, pacemaker
What is the treatment for tachycardia, which leads to low CO?
Cardioversion, antiarrhythmic drugs
What is the treatment for diminished inotropic state (contractility), leading to low CO?
Epi, dopamine, dobutamine, (amrinone), calcium, glucagon, digoxin
What is the treatment for excessive vasoconstriction, leading to low CO?
Lisinopril, hydralazine, prazosin, carvedilol, nitroglycerin, nitroprusside
What is the treatment for excessive or abnormal contractility leading to low CO?
Metoprolol, verapamil
What is atropine (sulfate)?
Atropine is a competitive muscarinic acetylcholine receptor antagonist. It is a naturally occurring tropane alkaloid extracted from deadly nightshade, Jimson weed, and other plants of the family Solanaceae.
Atropine dilates the pupils, increases heart rate, and reduces salivation and other secretions.
To what drug class does atropine belong?
Pharmacologic class => muscarinic receptor antagonist, belladonna alkaloid
Therapeutic class—antiarrhythmic, vagolytic, mydriatic
Describe the pharmacodynamics of atropine.
- Blocks the effects of ACh on the SA and AV nodes
=> increases conduction and HR
= > decreases secretions in various glands (e.g. salivary, bronchial, sweat)
Describe the pharmacokinetics of atropine.
- Given IV, endotracheally, and topically (in the eye)
What toxicity is associated with atropine?
- Avoid in patients with glaucoma.
- Also avoid in obstructive uropathy, GI obstruction, ileus, toxic megacolon
What special considerations should be noted in patients on atropine?
- Can cause agitation, confusion (especially in the elderly), delirium, disorientation
- Blurred vision
- Constipation
- Urine retention
- Watch out especially in older men with BPH
What is the dose/route for atropine?
- Indication: symptomatic bradycardia
- Give 0.5 to 1 mg IV push, may repeat
- Given pre-op to reduce secretions and to block cardiac vagal reflexes, give 0.4 mg IM one hour before anesthesia
To what drug class does dopamine (Intropin™) belong?
Pharmacologic : adrenergic and dopaminergic receptor agonist
Therapeutic class: inotropic agent; vasopressor
Describe the pharmacodynamics of dopamine.
- Stimulates dopamine receptors
- increases renal blood flow
- beta-1, and alpha-1 receptors at different infusion rates
Describe the pharmacokinetics of dopamine.
- Can only be infused IV
- Acts quickly within minutes
- Half-life brief (minutes), hence continuous infusion
What toxicity is associated with dopamine?
- Ectopy, tachycardia, angina, nausea, peripheral gangrene (excess vasoconstriction)
- Extravasation
What special conditions should be considered in patients on dopamine?
- Correct hypovolemia first
- Administer through large vein
- Prevent extravasation
- Monitor patient closely
What is the indication/dose/route of dopamine?
Indication: shock, CHF
Dose: 1 mcg/kg/min up to 30 mcg/kg/min
- low 1-2, moderate 2-10, high 10-30 mcg/kg/min
What is Dobutamine (Dobutrex™)?
Dobutamine is a sympathomimetic drug used in the treatment of heart failure and cardiogenic shock.
Its primary mechanism is direct stimulation of β1 receptors of the sympathetic nervous system.
To what class does dobutamine belong?
Pharmacologic: adrenergic receptor agonist
Therapeutic: positive inotropic agent
Describe the pharmacodynamics of dobutamine.
- Selectively stimulates beta-1 adrenergic receptors to increase contractility and SV resulting in increased cardiac output
- HR usually remains unchanged
Describe the pharmacokinetics of dobutamine.
- Can only be infused IV
- Acts quickly within minutes
- Half-life brief (minutes) => continuous infusion
What toxicity is associated with dobutamine?
- Ectopy, PVC’s, tachycardia, hypertension, hypotension
What special conditions should be noted in patients on dobutamine?
- Correct hypovolemia first
- Monitor patient closely
What are the indications/dose/route for dobutamine?
- 2.5-10 mcg/kg/min
- Rarely doses up to 40 mcg/kg/min may be needed
What is epinephrine best used for?
- Anaphylactic shock
- Cardiac arrest with asystole or fine VF
- After open heart surgery as patient is “warming up”
What is the best use/indication for lisinopril (vasodilator)?
- Afterload reduction
- Reduces excessive SVR
- Increases CO
Why is hydralazine not used by itself (vasodilator)?
- Not useful by itself because of reflex fluid retention and tachycarida
What is Bidil?
Bidil is a vasodilator made of hydralazine plus isosorbide dinitrate.
- It is very effective in African American patients more so than patients of other backgrounds
In what situation is nitroprusside used?
Nitroprusside is generally used in an ICU or coronary care unit because it must be given via IV.
- it is useful in reducing afterload
What agents reduce preload?
- Loop diuretics
- Powerful diuretic, acts on the loop of Henle, available po or iv - Thiazide diuretics
- Po only and less effective - Aldosterone antagonist diuretics
- Po only and can cause K retention
