Chapter 22 Positive Inotropic Drugs Flashcards
1
Q
Positive Inotropic Drugs
A
- Drugs that increase the force of myocardial contraction
- Used to treat heart muscle failure
- Cardiac glycosides (Digoxin)
- Phosphodiesterase inhibitors
2
Q
Cardiac Glycosides mechanism of action
A
- Increase myocardial contractility
- Changes the electroconduction of the heart by decreasing the rate of conduction (negative dromotropic effect), and prolonging the refractory period.
- Results in reduced HR (negative chronotropic effect) and improved cardiac efficiency
- Positive inotropic effect: increases the force and velocity of myocardial contraction
- Other effects include increase SV, decrease in BP, increase in coronary circulation, promotion of diuresis
3
Q
Digoxin
A
- Indications include atrial fibrillation
- Very narrow therapeutic window (normal range is 0.8-2 ng/mL) so drug levels must be monitored
- Low K+ levels increase its toxicity, but when someone is dig toxic, the K+ levels will be high because K+ stays outside of the cell. So electrolyte levels must be monitored.
- Adverse effects include: bradycardia, colored vision (seeing green/yellow/purple), halo vision, flickering lights, anorexia, nausea, vomiting, diarrhea
- Interactions: decrease absorption include antacids, antidiarrheals ( decrease effect); increase absorption include anticholinergics (increase effect); and barbituates reduce therapeutic effects
4
Q
Nursing considerations
A
- Take the apical pulse for 60 seconds before administering. If over 120/100 or below 60, hold the medication.
- Hold dose if patient is experiencing toxicity
- Monitor electrolytes
- Assess weight, and intake and output measures
5
Q
Digoxin toxicity
A
- Digoxin immune Fab (Digibind) therapy
- Results in hyperkalemia, dysrythmias
- Predisposing factors include hypokalemia, hepatic dysfunction, hypercalcemia, dysrhythmias, advanced age, and hypothyroid, respiratory, or renal disease
6
Q
Phosphodiesterase
A
- Positive inotropic response
- Vasodilation
