Diuretics. Mannitol (Amboss and UW)

Question 1

Osmotic diuretics?

Answer 1

Mannitol

Question 2

Mannitol mechanism of action? 2 mechanisms

Answer 2

Increase osmolality;

No saluresis

Question 3

Mannitol increase osmolality. Of what?

Answer 3

1. Serum osmolality and

2. Glomerular filtrate (aka tubular fluid osmolality)

Question 4

Mannitol. Increased serum osmolality mechanism?

Answer 4

Serum: ↑ shift of water into the intravascular space → ↑ binding of water → ↓ intracranial and intraocular pressure

Question 5

Mannitol. Increased glomerular filtrate osmolality mechanism?

Answer 5

↑ tubular fluid osmolarity → ↑ binding of water → ↑ urine production

Question 6

Mannitol filtration and absorption?

Answer 6

The osmotic diuretics are filtered freely in the glomeruli and are not reabsorbed throughout the entire tubule.

Question 7

What pressures decrease when used mannitol?

Answer 7

Decr. intracranial and intraocular pressure

Question 8

What is saluresis?

Answer 8

Saluresis aka natriuresis.

Increased renal excretion of sodium. Natriuresis also results in an increase in urine output (diuresis) because of the osmotic effect of sodium.

Question 9

Why osmotic diuretics are not useful for the saluretic treatment of edema?

Answer 9

Because osmotic diuretics (mannitol) does not cause saluresis.

Question 10

Mannitol indications?

Answer 10

Elevated ICP (e.g., cerebral edema)

Acute glaucoma

Prevention of acute renal injury in cases of oliguria

Forced renal excretion of substances (e.g., drugs or toxins), DRUGS OVERDOSE

Question 11

Mannitol contraindications?

Answer 11

Anuria
Progressive heart failure
Severe pulmonary edema
Severe dehydration

Question 12

Why mannitol is contraindicated in anuria?

Answer 12

With ineffective glomerular filtration and/or anuria, osmotic diuretics can lead to severe volume overload with subsequent pulmonary edema.

Question 13

Why mannitol is contraindicated in HF?

Answer 13

Osmotic diuretics initially increase circulating blood volume, causing cardiac strain.

Question 14

Why mannitol is contraindicated in pulmonary edema?

Answer 14

Due to circulatory overload

Question 15

Why mannitol is contraindicated in dehydratation?

Answer 15

Although extracellular fluid volume is increased, intracellular volume decreases.

Question 16

Side effects of mannitol?

Answer 16

Dehydration
Initial cardiac volumetric strain (itampa)
Metabolic and electrolyte imbalances

Question 17

What metabolic changes occur as complication of mannitol?

Answer 17

a. Effective glomerular filtration → hypernatremia (due to water decr in blood?)
b. Ineffective glomerular filtration or administration of very high doses → ↑ plasma osmolality → ↑ extracellular fluid volume → pulmonary edema, potassium fluctuations, hyponatremia or hypernatremia, and/or metabolic acidosis

Question 18

How flow water in the presence of mannitol?

Answer 18

down to its concentration gradient from the intracellular space to plasma (intravascular compartment).

Question 19

BBB and mannitol?

Answer 19

Mannitol does not cross BBB, therefore is used to treat elevated intracranial pressure (water from brain parenchyma goes to vasculature –> reduced intracranial volume and pressure).

Question 20

Intraparenchymal hemorrhage and midline shift. what medication?

Answer 20

Mannitol

Question 21

What is the origin of mannitol?

Answer 21

sugar alcohol

Question 22

Administration of mannitol?

Answer 22

Parenteral - nes blogai reabsorbuojasi, bet jeigu duo p/o, tai sukeltu osmotic diarrhea.

Question 23

how changes plasma Na concentration when mannitol effect ooccurs?

Answer 23

Na plasma concentration DECREASES because of water movement to intravascular compartment (DILUTIONAL HYPONATREMIA).

Bet tipo jeigu glomerular function is in tact, tai dahuja issifiltruoja vandes ir buna hypernatremia

Question 24

how changes renal blood flow when mannitol effect ooccurs?

Answer 24

Due to plasma volume expansion renal blood flow INCREASES –> Increased glomerular filtration and renal tubular flow.!!!!!

Question 25

Why there is reduced reabsorption of water in tubules in the presence of mannitol?

Answer 25

mannitol is filtered in glomerulus and not reabsorbed –> HYPEROSMOLAR GLOMERULAR FILTRATE –> reduced water reabsorption in tubules –> increased diuresis

Question 26

When manifest dehydratation if mannitol is used?

Answer 26

its delayed effect, its not acute complication

Question 27

Dehydratation effect on Na, glomerular filtrate osmolality and RBF due to mannitol?

Answer 27

Dehydratation -> hypernatremia, elevated glomerular filtrate osmolality, reduced renal tubular blood flow.

Question 28

Mannitol site of action in kidney?

Answer 28

proximal tubule and descending limb of Henle (both permeable to water)