Diuretics Flashcards by S Mosq

What are the basic functions of the kidney?

Cleansing of extracellular fluid (ECF); Excretion of metabolic wastes/foreign substances

Maintenance of extracellular volume and composition

Maintenance of acid-base balance

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What are the basic processes of the kidney?

Filtration
Active secretion
Reabsorption

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What is the normal urine output?

30 mL/hr

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What are diuretics?

Drugs that promote formation of urine

Drugs that accelerate the rate of urine formation

Drugs/substances that promote the formation and excretion of urine

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What are the major categories of diuretic drugs?

Loop diuretics
Thiazide diuretics
Osmotic diuretics
Potassium-sparing diuretics

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What determines the potency of diuretics?

The location of where the drugs work in the nephron to inhibit sodium and water reabsorption

The more sodium and water they inhibit from reabsorption, the greater the amount of diuresis and therefore the greater the potency

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What are 2 advantages to using diuretics?

Relatively low cost

Favorable safety profile

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What is the main problem with diuretic use?

The metabolic adverse effects that can result from excessive fluid and electrolyte loss

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What condition is diuretics a first-line drug for?

Hypertension

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What do diuretics do to arteries?

Cause arteriolar dilation

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What do diuretics do to the peripheral vascular system?

Arteriolar dilation decreases peripheral vascular resistance

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What do diuretics reduce?

Extracellular fluid volume
Plasma volume
Cardiac output

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What conditions can diuretics treat?

Hypertension

Heart failure

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Which diuretic is the most potent?

Loop diuretic

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What is the mechanism of action of loop diuretics?

Blocks reabsorption of sodium and chloride in the ascending limb of the loop of Henle which prevents reabsorption of water

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What is diuresis?

Increased/excessive production of urine

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When are loop diuretics particularly useful?

When rapid diuresis is needed because of their rapid onset of action

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What are the drug effects of loop diuretics?

Extensive diuresis and loss of fluid

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How long does the diuretic effect of a loop diuretic last?

At least 2 hours

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What are the cardiovascular effects of loop diuretics?

Due to decreased fluid volume from diuresis, there is a decreased return of blood to the heart

Reduced blood pressure
Reduced pulmonary vascular resistance
Reduced systemic vascular resistance
Reduced central venous pressure
Reduced left ventricular end-diastolic pressure

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What are indications for loop diuretics?

Pulmonary edema caused by heart failure or hepatic/renal disease

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What are contraindications of loop diuretics?

End stage renal disease
Anuria (failure of kidneys to produce urine)
Hepatic coma
Severe electrolyte loss

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What are the adverse effects of loop diuretics?

Severe dehydration
Hypotension
Hypokalemia
Ototxicity (toxic to the ear)
Hyperglycemia
Hyperuricemia

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What are the interactions with loop diuretics?

Digoxin - Hypokalemia results in increased digoxin toxicity

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What are some loop diuretics?

Furosemide (Lasix) Bumetanide (Bumex) Torsemide (Demadex)

What are some nursing implications for loop diuretics?

Monitor blood pressure Monitor electrolytes (especially K+) Monitor urine output Monitor fluid volume status

What are some things to educate the patient on concerning loop diuretics?

Monitor weight and blood pressure Change positions slowly Eat potassium rich foods Take medication early in the day

What is the range/level of hyperkalemia?

Serum potassium > 5.5 mEq/L

What are the signs and symptoms of hyperkalemia?

``` Generalized fatigue Weakness Paresthesia Palpitations Paralysis ```

What is paresthesia?

Abnormal sensation (“pins and needles”) caused chiefly by pressure on or damage to peripheral nerves

What is the most commonly used loop diuretic?

Furosemide (Lasix)

What is the mechanism of action of thiazide diuretics?

Blocks reabsorption of sodium and chloride in the early distal convulated tubule which prevents reabsorption of water

What is the drug effect of thiazide diuretics?

Maximum diuresis is less than loop diuretics Results in osmotic water loss

What are some thiazide diuretics?

Hydrochlorothiazide (HydroDiuril, HCTZ) | Chlorothiazide (Diuril)

What are the indications for thiazide diuretics?

Hypertension

Which diuretic is the first-line treatment for hypertension?

Thiazide diuretics

What are the contraindications of thiazide diuretics?

Renal insufficiency

What are adverse effects of thiazide diuretics?

``` Dehydration Hypotension Hypokalemia Hyperglycemia Hyperuricemia ```

What is hyperuricemia?

Excess of uric acid in bloodstream (40%)

What is hypokalemia?

Potassium deficiency Serum potassium level < 3.5 mEq/L

What are nursing implications of thiazide diuretics?

Monitor blood pressure Monitor electrolytes (especially K+) Monitor fluid volume status

What are some things to educate the patient on concerning thiazide diuretics?

Monitor weight and blood pressure Change positions slowly Eat potassium rich foods (drug is potassium wasting) Take medication early in the day to avoid nocturia

What is the mechanism of action of potassium-sparing diuretics?

Blocks the action of aldosterone in the distal tubule which results in potassium retention and the excretion of sodium and water

What is the drug effect of potassium-sparing diuretics?

Counteracts the potassium-wasting effect of more powerful diuretics Mild diuresis effect

What are some potassium-sparing diuretics?

Spironolactone (Aldactone) Amiloride (Midamor) Triamterene (Dyrenium)

What are indications for potassium-sparing diuretics?

Frequently combined with thiazide and loop diuretics to counterbalance potassium-wasting

What are contraindications of potassium-sparing diuretics?

Hyperkalemia Anuria Renal failure

What are adverse effects of potassium-sparing diuretics?

Hyperkalemia (if used alone) Impotence Gynecomastia (swelling of breasts is males) Menstrual irregularities

What are interactions with potassium-sparing diuretics?

Angiotensin converting enzyme (ACE) inhibitors, potassium supplements -> Hyperkalemia Angiotensin receptor blockers (ARBs) Direct renin inhibitors

What are some nursing implications of potassium-sparing diuretics?

Monitor blood pressure Monitor electrolytes Monitor fluid and volume status

What are some things to teach patients concerning potassium-sparing diuretics?

Avoid salt substitutes that contain potassium | Keep log of blood pressure and weight

What is the mechanism of action of osmotic diuretics?

Decreases cerebral edema by raising serum osmolality which draws fluid into vascular space Creates osmotic effect in nephron causing increased secretion of water

What is the drug effect of osmotic diuretics?

The greater the amount of mannitol (osmotic diuretic) the greater the diuresis (available 5-25%)

What are some osmotic diuretics?

Mannitol (Osmitrol)

What are indications for osmotic diuretics?

Cerebral edema | Prevention of kidney injury in hypovolemic shock

What is hypovolemic shock?

An emergency condition in which severe blood or fluid loss makes the heart unable to pump enough blood to the body

What are contraindications of osmotic diuretics?

Renal failure | Pulmonary edema caused by heart failure

What are adverse effects of osmotic diuretics?

Can precipitate heart failure and pulmonary edema

What are some nursing implications of osmotic diuretics?

``` Monitor blood pressure Monitor electrolytes Monitor fluid volume status Use a filter in the IV tubing Monitor signs/symptoms of heart failure ```

What is normal serum potassium level?

3.5 - 5.0 mEq/L

What are some evidences of normal kidney function?

Urine output of at least 30 mL/hr Serum creatinine level between 0.6 - 1.2 mg/dL BUN levels between 10 - 20 mg/dL

What are the signs and symptoms of hypokalemia?

``` Early: Hypotension Lethargy Mental confusion Muscle weakness Nausea ``` Late: Cardiac irregularities Neuropathies Paralytic ileus

What are some potassium rich foods?

``` Bananas Potatoes Dried fruit Tomatoes Spinach Citrus fruits ```

What is the effect of aldosterone on the distal tubule of the nephron?

Aldosterone regulates the filtration of sodium in exchange for potassium or hydrogen ions in the distal tubule

Where in the nephron is the osmotic diuretic action site?

Proximal tubule | Descending loop of Henle

Where in the nephron is the loop diuretic action site?

Ascending loop of Henle

Where in the nephron is the thiazide diuretic action site?

Distal tubule

Where in the nephron is the potassium-sparing diuretic action site?

Distal tubule to collecting duct

How much sodium is reabsorbed back into the bloodstream in the proximal tubule?

60 - 70%

How much sodium is reabsorbed back into the bloodstream in the ascending loop of Henle?

20 - 25%

Where does the remaining 5 - 10% of sodium resorption take place?

Distal tubule