Test 2: 32: diuretics part 2

Question 1

— are osmotic diuretics

Answer 1

Mannitol, Glycerol, Glucose, Urea, Isosorbide

Freely filtered at the glomerulus
* Not resorbed by the renal tubule
* Chemically inert

Question 2

how does mannitol work in the kidney

Answer 2

filtered from blood into the tubule

will act as osmotic diuretic and pull water into tubule → increased urine output

Question 3

before giving mannitol what should you do to med

Answer 3

warm and filter

can form crystals at low temps

mannitol is a sugar alcohol

Question 4

acute effects of mannitol

Answer 4

will ↑ plasma osmolarity = pulls water into arteries

• this causes increased IV volume
• will dilute hematocrit and sodium in the blood
• decreases blood viscosity

directly reduces vascular tone
scavanges free radicals

Question 5

renal effects of mannitol

Answer 5

freely filtered by glomerulus

will pull water into lumen →Dilutes concentration of electrolytes, reducing their reabsorption and promoting diuresis

makes dilute urine

May increase cortical and medullary blood flow via vasodilation

Question 6

adverse effects of mannitol

Answer 6

• Expansion of intravascular volume may not be tolerated in patients with cardiovascular disease
• can cause ↑sodium from water loss
• rapid administration can cause hypotension and nausea – administer over 15-20 minutes
• Osmotic nephrosis – Prolonged administration or very high dosage may cause acute kidney injury (mannitol gets taking into tubule cell and causes swelling)

Question 7

contraindications to giving mannitol

Answer 7

• Congestive heart failure
• Anuric renal failure
• Severe dehydration
• Ongoing intracranial hemorrhage??

Question 8

three disease to use mannitol

Answer 8

Elevated Intracranial Pressure
* Head trauma, prolonged seizures, intracranial mass,
cerebral edema post CPR

Acute Kidney Injury

Acute Glaucoma

Question 9

cerebral perfusion pressure is measured by

Answer 9

CPP= MAP- ICP
(mean arterial pressure) - (intracranial pressure

Question 10

monro-kellie doctrine

Answer 10

the amount of stuff in the skull needs to remain constant

if you increase one, you must decrease another to maintain healthy pressure

Question 11

how does mannitol help elevated intracranial pressure

Answer 11

will pull fluid from brain into the vessels → decrease intracranial pressure and volume

decreased blood viscosity enhances perfusion and O2 delivery to the brain → causes compensatory vasoconstriction → decrease in blood volume within the brain

Diuretic effect sustains the reduction in ICP

Question 12

can you give mannitol with pt with hypovolemia and high ICP

Answer 12

no

would cause more harm then good

would decrease overall fluid volume

should use hypertonic saline: will decrease ICP and increase blood volume

Question 13

three ways mannitol helps AKI

Answer 13

• increased urine flow can “flush” away casts obstructing renal tubule
• Tubular cell swelling is reduced, increasing tubular diameter and improving flow
• Increased water in tubule dilutes nephrotoxins

Question 14

how does mannitol effect intraocular pressure

Answer 14

• Intraocular water drawn into hyperosmolar plasma
• Vitreous shrinks and lens moves posteriorly opening up the iridocorneal angle facilitating aqueous drainage
• Useful in emergency treatment of acute glaucoma

Question 15

carbonic anhydrase inhibtors will cause excretion of —

Answer 15

bicarb and Na

Acetazolamide, Methazolamide, Dorzolamide (topical for ophthalmic use)

Question 16

— are some carbonic anhydrase inhibitors

Answer 16

Acetazolamide, Methazolamide, Dorzolamide (topical for ophthalmic use)

will cause ↑ excretion of Na and bicarb

Question 17

when to not use mannitol

Answer 17

CHF
anuric renal failure
severe dehydration
ongoing intracranial hemorrhage

Question 18

when not to give carbonic anhydrase inhibitor

Answer 18

alkaline urine → can form bladder stones

↑urine pH increases renal reabsorption of ammonia- AVOID in pt with severe hepatic dysfunction

metabolic acidosis: AVOID in pt that can’t compensate by increasing their ventilation - pulomonary disease

decreased iodine uptake by thyroid gland: AVOID in pt with hypothyroidism

Question 19

when to use carbonic anhydrase inhibitors

Answer 19

glaucoma: decreases aqueous humor production

hydrocephalus?: decreases CSF production

Question 20

dog post hit by car and seizure, with no heart murmus, strong pulse.
how to treat?

Answer 20

IV mannitol-
will decrease ICP by pulling fluid out of brain.

Reduction of blood viscosity enhances perfusion and oxygen delivery to the brain which causes vasocontriction→ blood volume in the brain