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NURS 2820U > Diuretics and Agents Affecting the Volume and Ion Content of Body Fluids - Cardiac 1 > Flashcards

Diuretics and Agents Affecting the Volume and Ion Content of Body Fluids - Cardiac 1 Flashcards

1
Q

What do diuretics increase?

A

The output of urine

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2
Q

What are diuretics used for?

A
  1. Treats hypertension
  2. Helps the body get rid of excess fluid with heart failure, cirrhosis, or kidney disease
  3. Prevents renal failure
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3
Q

What are the 4 regions of nephrons?

A
  1. Glomerulus
  2. Proximal convoluted tubule (PCT)
  3. Loop of Henle
  4. Distal convoluted tubule
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4
Q

What are the 3 basic functions of the kidneys?

A
  1. Cleanses ECF, while also maintaining the ECF volume and composition
  2. Maintains acid-base balance
  3. Excretes metabolic wastes and foreign substances
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5
Q

Which one of the kidneys basic functions affects the diuretics the most?

A

Maintenance of ECF volume and composition

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6
Q

What are the kidney’s three basic processes that affect extracellular fluid (ECF)

A

filtration, reabsorption, and active tubular secretion.

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7
Q

How does the 3 basic processes that affect ECF maintain homeostasis?

A

The kidneys filter plasma, reabsorb what the body needs, and excrete a small amount of urine to cleanse ECF and maintain balance.

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8
Q

What does filtration do?

A

First step in urine formation, and happens at the glomerus

Small molecules like (glucose and wastes) pass through, while large molecules (proteins) stay in the blood.

It is nonselective and doesn’t regulate urine composition.

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9
Q

What happens at the reabsorption process?

A

Returns most water, electrolytes, and nutrients, while excreting wastes. Solutes are actively reabsorbed, and water follows passively.

Diuretics interfere with reabsorption.

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10
Q

What happens at the active tubular secretion process?

A

Uses two pumps in the PCT to transport organic acids and bases from plasma into the nephron, helping excrete wastes, drugs, and toxins.

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11
Q

Why is the reabsorption of sodium and chloride ions important, and where does it occur?

A

Sodium and chloride are the main solutes in the filtrate, and their reabsorption occurs at specific sites in the nephron

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12
Q

What happens in the proximal convoluted tubule (PCT) during reabsorption?

A

Has a high reabsorptive capacity.

Reabsorbs 65% of sodium and chloride, all bicarbonate and potassium, and water, keeping urine isotonic with sodium and chloride remaining in significant amounts.

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13
Q

What happens in the loop of Henle during reabsorption?

A

The descending limb of the loop of Henle reabsorbs water, concentrating the urine.

In the ascending limb, sodium and chloride are reabsorbed without water, restoring the urine’s original tonicity.

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14
Q

What happens in the distal convoluted tubule during reabsorption?

A

In the distal convoluted tubule, 10% of sodium and chloride are reabsorbed, and water follows naturally.

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15
Q

What happens in the distal nephron, in regards to reabsorption and how is it regulated?

A

Aldosterone regulates sodium reabsorption and potassium secretion, while ADH controls urine concentration.

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16
Q

What reabsorption does diuretics block?

A

sodium and chloride reabsorption.

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17
Q

How do diuretics block sodium and chloride reabsorption?

A

Creates osmotic pressure within the nephron and prevent passive reabsorption of water.

It causes water and solutes to be retained within the nephron and promotes the excretion of both.

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18
Q

Why are diuretic drugs most effective when acting early in the nephron?

A

Because the amount of solute in the nephron decreases as the filtrate moves from the proximal tubule to the collecting duct, making early intervention more impactful.

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19
Q

What are the potential side effects of diuretics?

A

Can cause hypovolemia, acid-base imbalance, and altered electrolyte levels by interfering with normal kidney function to promote water excretion.

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20
Q

How can the adverse effects of diuretics be minimized?

A

By using short-acting diuretics

Timing administration to allow the kidney to function without the drug between doses, giving it time to readjust the ECF.

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21
Q

What is considered a high efficacy diuretic?

A

Sulphamoyl Derivatives such as Furosemide

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22
Q

What is considered a medium efficacy diuretic?

A

Thiazides (Benzothiadiazines): Hydrochlorthiazide

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23
Q

What is a weak/adjunctive diuretic?

A

Carbonic anhydrase inhibitors such as Acetazolamide

Potassium-sparing diuretics (aldosterone antagonists) such as Spironolactone

Potassium Sparing Diuretics(renal epithelial Na+ channel) such as Amiloride

Osmotic diuretics such as Mannitol

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24
Q

Why are loop diuretics considered the most effective?

A

They produce the greatest loss of fluid and electrolytes, acting on the loop of Henle.

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25
Q

What is Furosemide (Lasix) and how does it work?

A

A loop diuretic that blocks sodium and chloride reabsorption in the ascending limb of the loop of Henle, preventing water reabsorption and causing profound diuresis.

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26
Q

How is Furosemide administered and how quickly does it work?

A

Can be given orally, intravenously, or intramuscularly.

Oral administration begins diuresis in 60 minutes (lasting 8 hours)

IV administration works within 5 minutes and lasts 2 hours, used in critical situations.

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27
Q

Why is Furosemide generally reserved for severe cases?

A

Is a powerful diuretic

Typically used in emergencies that require rapid fluid removal, and should be avoided when less potent diuretics would be sufficient.

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28
Q

What conditions justify the use of Furosemide?

A

Pulmonary edema
Unresponsive edema
Uncontrolled hypertension
In patients with severe renal impairment

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29
Q

Can Furosemide be combined with other diuretics?

A

An be combined with a thiazide diuretic if necessary

There is no benefit to combining it with another loop diuretic.

30
Q

How do thiazides compare to loop diuretics in terms of function?

A

Increase excretion of sodium, chloride, potassium, and water, similar to loop diuretics, but their maximum diuresis is lower

They are ineffective when urine flow is decreased.

31
Q

What are the side effects of thiazide diuretics?

A

Thiazides can elevate plasma levels of uric acid and glucose.

32
Q

What is Hydrochlorothiazide and why is it commonly used?

A

Most widely used thiazide diuretic,

Primarily for treating hypertension, as it blocks sodium and chloride reabsorption in the distal convoluted tubule, increasing urine production.

33
Q

What limits the effectiveness of thiazides in promoting diuresis?

A

Thiazides are ineffective when GFR is low and cannot be used in patients with severe renal impairment.

34
Q

How long does it take for thiazides to take effect and how long do they last?

A

Diuresis begins about 2 hours after oral administration Peaks in 4 to 6 hours
Lasts up to 12 hours.

35
Q

What are the therapeutic uses of thiazides?

A

Thiazides are primarily used to treat hypertension often as the first choice

preferred for mobilizing edema in conditions like mild to moderate heart failure, and hepatic or renal disease.

36
Q

Are thiazides effective alone for hypertension?

A

Thiazides can control blood pressure in many hypertensive patients on their own, but some may require multiple-drug therapy.

37
Q

What 2 responses can the potassium-sparing diuretics elicit?

A

Modest increase in urine production

Substantial decrease in potassium excretion

38
Q

Why are potassium-sparing diuretics often combined with other diuretics?

A

They are used to counteract potassium loss caused by thiazide and loop diuretics due to their strong ability to decrease potassium excretion.

39
Q

Why are potassium-sparing diuretics rarely used alone?

A

Their diuretic effects are limited, so they are usually combined with other diuretics for better effectiveness.

40
Q

How does spironolactone (Aldactone) work?

A

Spironolactone blocks aldosterone in the distal nephron, leading to potassium retention and increased sodium excretion.

41
Q

Why is the diuretic effect of spironolactone considered scanty?

A

Because most sodium has already been reabsorbed by the time the filtrate reaches the distal nephron.

42
Q

What is the role of aldosterone in the distal nephron?

A

Aldosterone promotes sodium uptake in exchange for potassium secretion.

43
Q

Why are the effects of spironolactone delayed?

A

It blocks new protein synthesis but doesn’t stop existing transport proteins, so effects take up to 48 hours.

44
Q

How does aldosterone affect sodium and potassium transport in the distal nephron?

A

Stimulates cells to produce proteins needed for sodium uptake and potassium secretion.

45
Q

What happens when spironolactone prevents aldosterone’s action?

A

It stops the production of new transport proteins, leading to potassium retention and sodium excretion once the current proteins are no longer active.

46
Q

What are the primary therapeutic uses of spironolactone?

A

hypertension, edema, and heart failure.

47
Q

Why is spironolactone often combined with thiazide or loop diuretics?

A

To counteract the potassium-wasting effects of thiazide or loop diuretics while making a small contribution to diuresis.

48
Q

How does spironolactone benefit patients with severe heart failure?

A

It reduces mortality and hospital admissions by blocking aldosterone’s harmful effects on the heart and blood vessels.

49
Q

What are the main adverse effects of spironolactone?

A

Spironolactone can cause hyperkalemia, leading to fatal dysrhythmias, and endocrine effects like gynecomastia, menstrual irregularities, impotence, hirsutism, and deepened voice.

50
Q

How should hyperkalemia caused by spironolactone be managed?

A

Discontinue the med
Restrict potassium intake
Consider insulin to lower potassium by promoting cellular uptake.

51
Q

Why should caution be used when combining spironolactone with certain medications?

A

Some meds can raise potassium levels, increasing the risk of hyperkalemia.

52
Q

What precautions should healthcare workers take when handling spironolactone?

A

Wear a protective gown and two sets of gloves when cutting or crushing spironolactone tablets to prevent fetal harm and reproductive risks.

53
Q

Why is spironolactone combined with thiazide or loop diuretics?

A

To counteract potassium loss caused by the more powerful diuretics.

54
Q

What is the mechanism of action of triamterene?

A

Directly inhibits sodium-potassium exchange in the distal nephron, reducing sodium reabsorption and potassium secretion.

55
Q

How does triamterene differ from spironolactone in onset of action?

A

Triamterene acts faster than spironolactone, with effects developing in hours because it directly inhibits ion transport.

56
Q

What are the therapeutic uses of triamterene?

A

Treats hypertension and edema, either alone for mild diuresis or in combination with other diuretics to enhance diuresis and counteract potassium loss.

57
Q

Why is triamterene often combined with diuretics like furosemide or hydrochlorothiazide?

A

To enhance diuresis and counteract the potassium-wasting effects of more powerful diuretics.

58
Q

What is the most significant adverse effect of triamterene?

A

Excessive potassium accumulation leading to hyperkalemia

59
Q

When should caution be used with triamterene to avoid hyperkalemia?

A

When combined with potassium supplements, salt substitutes, potassium-sparing diuretics, ACE inhibitors, ARBs, or direct renin inhibitors.

60
Q

What are common side effects of triamterene?

A

Nausea, vomiting, leg cramps, dizziness, and rarely, blood dyscrasias.

61
Q

What is the primary action of amiloride?

A

Blocks sodium-potassium exchange in the distal nephron, reducing potassium loss and producing modest diuresis.

62
Q

What is amiloride primarily used for?

A

To counteract potassium loss caused by thiazide or loop diuretics.

63
Q

What is the major adverse effect of amiloride?

A

Hyperkalemia

64
Q

What makes mannitol an effective osmotic diuretic?

A

freely filtered at the glomerulus, minimally reabsorbed, minimally metabolized

65
Q

How does mannitol increase urine flow?

A

It remains in the nephron, creating an osmotic force that inhibits water reabsorption, thus increasing urine flow.

66
Q

What is the relationship between the concentration of mannitol and diuresis?

A

The higher the concentration of mannitol in the filtrate, the greater the diuresis.

67
Q

How is mannitol administered and absorbed?

A

Mannitol is given parenterally (IV), as it does not diffuse across the GI epithelium.

68
Q

How long does diuresis last after mannitol administration?

A

Diuresis begins in 30-60 minutes and lasts 6-8 hours.

69
Q

What are the therapeutic uses of mannitol?

A
  1. Helps preserve urine flow and prevent renal failure
  2. Reduction of intracranial pressure
  3. Reduction of intraocular pressure
70
Q

What are the adverse effects of mannitol?

A

Can cause edema
Can worsen heart failure or cause pulmonary edema

NURS 2820U (4 decks)

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