Chapter 28: Diuretic Drugs
How long after administering furosemide intravenously to a patient should the nurse anticipate the beginning of diuresis? A. 1 minute B. 5 minutes C. 30 minutes D. 60 minutes
B. 5 minutes The effects of IV furosemide begin within 5 minutes of administration and last 2 hours. IV therapy is used in critical situations (e.g., pulmonary edema) that demand immediate mobilization and elimination of fluid.
The nurse instructs a patient who takes an angiotensin-converting enzyme (ACE) inhibitor to avoid foods that are good sources of potassium, but the patient continues to exhibit a high serum potassium level with normal renal function. Which diuretic should the nurse administer to help prevent adverse effects of hyperkalemia for this patient? A. Mannitol (Osmitrol) B. Bumetanide C. Amiloride (Midamor) D. Spironolactone (Aldactone)
B. Bumetanide The nurse wants to administer a diuretic that aids the excretion of potassium because this will help diminish the patient's tendency to retain potassium. Therefore, the nurse wants to administer a loop diuretic, such as bumetanide, because these agents induce excretion of potassium along with sodium and water. Aldosterone, a hormone secreted from the adrenal cortex, induces sodium retention and potassium excretion. Spironolactone blocks the action of aldosterone, leading to sodium loss and potassium retention. Mannitol is an osmotic diuretic that has a minor effect on serum electrolytes; it will not help reduce the patient's serum potassium level. Amiloride and spironolactone are contraindicated because although they induct the excretion of sodium effectively, they also induce the retention of potassium.
A patient with heart disease has taken furosemide (Lasix) for 3 months and complains of fatigue and palpitations to the health care provider. Once the provider has determined that the patient's condition is stable, which information should the nurse include in patient teaching to help this patient feel better? A. Eat additional lean meat and fish. B. Eat bananas and orange juice daily. C. Intensify your daily exercise program. D. Seek emergency care for palpitations.
B. Eat bananas and orange juice daily. The nurse instructs the patient to eat more bananas and to drink orange juice because these foods are good sources of potassium. The nurse provides these instructions because the patient takes furosemide, a loop diuretic that excretes a significant amount of potassium with sodium. This occurs because the drug acts in the ascending loop of Henle. These instructions are also proper because the patient complains of fatigue and palpitations, both of which can be caused by hypokalemia. Increasing the consumption of meat and fish is proper if the patient is anemic. The nurse avoids instructing the patient to increase exercise without provider approval. Emergency treatment is not necessary for palpitations unless the patient has syncope or other clinical indicators of hypotension or low cardiac output.
Which diuretic is the drug of choice for the prevention of tissue damage after a closed head injury? A. Mannitol (Osmitrol) B. Metolazone (Demedex) C. Spironolactone (Aldactone) D. Hydrochlorothiazide (HydroDIURIL)
A. Mannitol (Osmitrol) Mannitol is the drug of choice to prevent increased intracranial pressure after a closed head injury; although it works along the entire length of the nephron, it reduces intracranial pressure and cerebral edema by reducing cellular edema. Metolazone and furosemide are loop diuretics, and hydrochlorothiazide is a thiazide diuretic; they are of little benefit in reducing cerebral edema.
The nurse prepares to administer digoxin (Lanoxin) and furosemide (Lasix) to a male patient. For which findings should the nurse monitor to help prevent a serious complication of therapy? (Select all that apply.) A. Poor appetite B. Seizure activity C. Irritable reflexes D. Bilateral crackles E. Irregular heartbeat F. High blood pressure
A. Poor appetite C. Irritable reflexes E. Irregular heartbeat This patient is at high risk for ventricular dysrhythmias because of the combination therapy. Digoxin is used to treat heart failure and atrial dysrhythmias; however, the risk of serious digoxin toxicity resulting in ventricular dysrhythmias increases greatly when the patient has hypokalemia. Unfortunately, this patient is at high risk for hypokalemia because he also takes furosemide, a loop diuretic, which promotes potassium loss. Hence the nurse needs to detect the signs of hypokalemia and ventricular irritability—including anorexia, irregular heart rate, and hyperreflexia—early. Digoxin toxicity and hypokalemia are unlikely to lead to convulsions, accumulation of pulmonary fluid, or increased blood pressure.
The potency of a diuretic depends on what? A. Dosage of diuretic B. Ability to reabsorb water C. Site of mechanism of action D. Strength of sodium filtration
C. Site of mechanism of action Most diuretics share a basic mechanism of action: blockade of sodium and chloride reabsorption. The degree to which a diuretic can reabsorb sodium depends on where the diuretic acts in the nephron because certain locations in the nephron reabsorb sodium better than do others. For example, the proximal convoluted tubules reabsorb 60% to 70% of the sodium from the glomerular filtrate. By blocking the reabsorption of these solutes, diuretics prevent the passive reabsorption of water. The dosage determines the strength of a specific diuretic's action at a specific site; however, depending on the medication, a high dosage of a low-potency medication can be less effective than a normal dosage of a high-potency diuretic. The only location in the nephron that reabsorbs water is the collecting ducts, and diuretics do not work in the collecting ducts. In the glomerulus, all solutes are filtered and the degree of sodium filtration depends on health of the kidneys, solute concentration in the blood, and renal artery pressure.
What prevents the elimination of very diluted urine? A. Aldosterone B. Hypernatremia C. Glomerular filtration D. Antidiuretic hormone
D. Antidiuretic hormone Antidiuretic hormone (ADH), known as the water-conserving hormone, acts on the collecting duct to regulate conservation of water by increasing the water permeability of the collecting ducts; this decreases the amount of water eliminated in urine. Aldosterone acts to conserve sodium. Hypernatremia works to pull fluid from the interstitial spaces into the intravascular space; however, without ADH and adequate renal function, the sodium level may be irrelevant. Glomerular filtration works to remove solutes and water from the arterial blood, so glomerular filtrate is not diluted.
A patient who needs a heart transplant has a very low cardiac output and severe peripheral edema. Which diuretic should the nurse administer to help achieve fluid balance in this patient? A. Metolazone (Zaroxolyn) 10 mg/day by mouth B. Mannitol (Osmitrol) 100 g/day IV infusion C. Bumetanide (Bumex) 2.5 mg by mouth twice daily D. Furosemide (Lasix) 40 mg IV push over 10 minutes
D. Furosemide (Lasix) 40 mg IV push over 10 minutes When cardiac output is low, renal perfusion is low; this signals the sympathetic nervous system to vasoconstrict and to conserve sodium and water. To overcome this problem, the nurse administers furosemide in an IV push because loop diuretics function in low-cardiac output states. The infusion rate of the furosemide IV push should not exceed 4 mg/min, so the nurse infuses 40 mg over 10 minutes or more. Metolazone and bumetanide are poor choices because they are administered by mouth. It is unlikely that the patient is taking oral medications; however, and more importantly, oral medications take longer to act and may be less effective when administered by mouth as a result of hepatic metabolism. Mannitol is not indicated for peripheral edema.
Which diuretic is a poor choice for a patient who has gout? A. Mannitol (Osmitrol) B. Acetazolamide (Diamox) C. Spironolactone (Aldactone) D. Hydrochlorothiazide (HydroDIURIL)
D. Hydrochlorothiazide (HydroDIURIL) Hydrochlorothiazide is a thiazide diuretic, which can cause an increased uric acid level, so it is a poor choice for a patient who has gout because gout is a condition of impaired uric acid metabolism resulting in uric acid accumulation. Mannitol, acetazolamide, and spironolactone are better choices for this patient because they are less likely to increase the uric acid level.
The mechanism of action for most diuretics involves impairment of what? A. Water filtration B. Solute filtration C. Water reabsorption D. Solute reabsorption
D. Solute reabsorption Most diuretics act by impairing solute reabsorption. This may take place in the proximal or distal convoluted tubules or in the loop of Henle. Solute and water filtration takes place in the glomerulus. The primary sites for water reabsorption are the collecting ducts.
Disseminated intravascular coagulopathy (DIC) and severe diffuse edema develop in a 24-year-old female patient after a serious motor vehicle accident (MVA). Which of these diuretics can the nurse administer to avoid aggravating the coagulopathy? (Select all that apply.) A. Furosemide (Lasix) B. Mannitol (Osmitrol) C. Triamterene (Dyrenium) D. Acetazolamide (Diamox) E. Spironolactone (Aldactone) F. Hydrochlorothiazide (HydroDIURIL)
B. Mannitol (Osmitrol) Among the listed medications, mannitol is the only diuretic that can be administered to this patient to avoid aggravation of a coagulopathy. Furosemide is contraindicated because it can cause thrombocytopenia and bone marrow suppression. Triamterene and spironolactone are contraindicated because they are potassium-sparing diuretics, and the patient is likely to be hyperkalemic as a result of hemolysis and injuries sustained in the crash. In addition, triamterene is a fairly weak diuretic that can cause megaloblastic anemia. Acetazolamide can cause hematuria and melena, which might confound evaluation of the patient's hematologic therapy; the medical team would not be able to determine whether the hematuria and melena were the result of the diuretic or the coagulopathy. Finally, hydrochlorothiazide is contraindicated because it can cause bone marrow suppression, which could lead to thrombocytopenia.
