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Flashcards in Diuretics Deck (56):
1

two aspects of perfusion think renal function

bad renal function, how its addressed on bypass

2

PROXIMAL CONVULTED TUBULe diuretics

CARBONIC ANHYDRASE INHIBTORS ADENOSINE ANTAGONIST

3

thick ascending limb loop of henle drugs diuretics

loop diuretics

4

distal convoluted tubule diuretics

thiazides

5

cortical collecting tubule diuretics

K sparing diuretics adenosine antagonists

6

medullary collecting ducts diuretics

vasopressin antagonists

7

common uses for diuretiucs

CHF,HEPATIC ASCITES,NEPHROTIC SYNDROME,HTN,

8

Hepatic ascites

increased portal vein pressure liver starts to sweat fluid. end stage liver failure colloid pressure decreases because of decreased protein. goes into abdomen. think african kids starving

9

nephrotic syndrome

high aldosterone levels. lose glucose amino acids and proteins. colloid pressure goes down. causes fluid overload

10

htn

stiff arteries need fluid relief

11

diuretic categories

carbonic anhydrase inhibitors. loop diuretics, thiazides, potassium sparing diuretics

12

#1: Carbonic Anhydrase (CA) Inhibitors

least important to us not very strong. • *Work by inhibiting carbonic anhydrase in the proximal tubule epithelium
• Carbonic anhydrase catalyzes
• With CA blocked, the reaction shifts to the right and bicarbonate accumulates in the urine.
odium is less able to be exchanged for H+ in the tubules so H+ is retained while Na+ is lost (with the bicarbonate).
* Sooo...urine becomes more alkaline (explain), water follows the bicarbonate into the tubules (causing diuresis) and the patient experiences a metabolic acidosis (explain again).

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-Acetazolamide

(Diamox) Carbonic Anhydrase (CA) Inhibitor. Rarely used in cardiovascular surgery (why?) causes metabolic acidosis
-You may see patients on acetazolamide who have glaucoma
...or high-elevation sickness

14

#2: Loop Diuretics

• Act on the ascending Loop of Henle
-Also called “High Ceiling” diuretics because the dose-response curve is close to linear (that is, there’s no “ceiling”)

15

how loop diuretics work

Loop diuretics work by blocking the co-transport of Na+/K+/2Cl ̄ from the tubular lumen back into circulation.
• So much NaCl is not resorbed that downstream nephron sites cannnot compensate for that loss.

16

loop diuretics are most

efficacious (what’s this?) of all diuretics and work incredibly fast (within minutes when given IV).
• Called the “yellow zipper” drugs of human medicine (or the “waiting room puddle” drugs in veterinary medicine) work fast. good for bypass

17

loop diuretics additional mechanism

Loops” also work to increase renal blood flow by inducing the expression of COX-2
• COX-2 is referred to as the “ungood” cyclooxygenase NSAIDS (what’s this?) preferentially block in inflamed tissues

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cyclooxygenase produces

prostaglandins which are powerful
vasodilators of renal arteries.

19

nsaids may

may interfere with loop diuretic function in
compromised patients (hepatic cirrhosis,
nephrotic syndrome)

20

loop diuretics doc for

patients w/ renal function. pulmonary edema because they act fast

21

doc for hypercalcemia and hyperkalamia

loop diuretics

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loop diuretics aka

non potassium sparing diuretics

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loop diuretics perfusion uses

1) Get rid of extra fluid on bypass (duh!)
*Chemical “hemoconcentrators”
2) Get rid of excess K⁺
*What is normal K⁺ again?
3) Help maintain urine production/renal
function (***!!!) in low output states on
bypass (what might these be?) may be deliterious. may be giving lasix when you dont need it like when youre down on flow

24

sides of loops

hypotension,hyperuricemia, hypokalemia,hypomagnesemia,ototoxicity (aminoglycoside antibiotics)

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furosemide

lasix. • Very commonly used during and peri-bypass.
• Very inexpensive
• Has been used forever
• Wide margin of safety/therapeutic window
therefore the potential for “We always put
some lasix in the pump” mentality
• ~2 hour duration of action when given IV (on
pump)

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ethacrynic acid

edecrin. Loop diuretic. Less commonly used than furosemide
• Like furosemide but greater potential for
oxotoxicity

27

Bumetanide and Torsemide

(Bumex) and (Demadex). -Like furosemide and ethacrynic acid
-Much less frequently used
-Generally utilized as “physician’s
preference” or when desired response is
not achieved by furosemide.

28

Thiazide Diuretics

Act on the cortical
region of the Ascending
Loop of Henle
*Also called “Ceiling Diuretics” because of their
“flattening” dose/response curve

29

thiazide diuretics. how they work

-Thiazide diuretics work blocking Na⁺/Cl¯
transport/reabsorption on the luminal side of
the thick part of the Ascending Loop of Henle
and the Distal Convoluted Tubule.
-Consequently, NaCl concentrates in the
tubular fluid (and H₂O obediently follows =
increased urine production)

30

thiazide caveot

This also means that thiazides have to
actually get into the tubular lumens via renal
excretion…
…so thiazides lose efficacy in patients with
decreased renal function. need high urine production to get in. lasix can work on blood side

31

Thiazide Diuretics similar to loops because

Like “Loops”, thiazides increases renal blood
flow through COX-2 inducement of
prostaglandin synthesis.
• Structurally related to Acetazolamide, but
cause much more diuresis.

32

original diuretic used for edema

chlorothiazide. *Chlorothiazide is the only thiazide available
for parenteral use (of relevance to you!)
*Typical adult pump dose is 500mg

33

thiazide effects on electrolytes

increased urinary excretion of Na,K, vol. decrease excretion of calcium (sparing)

34

Thiazide Diuretics
Perfusion Uses

Like the “Loops” thiazides get rid of extra
(edema) fluid and potassium.
- systemic vascular resistance due to
relaxation of arteriolar smooth muscle
*So how do these two effects
synergize?getting rid of fluid and creating more capacitance for fluid by dilating
These are “second-line” treatments (after
“Loops” for the edema of heart failure.
-HTN

35

thiazide advantage over loop

Thiazides promote the reabsorption of
calcium.
*Compared to “Loops”, long-term
use results in significantly less
decrease in bone density (hip
fractures are decreased by 1/3rd)

36

ince thiazides can (uniquely) cause the
production of hyperosmolar urine (what’s
this?) it’s used in diabetes insipidus (?)

allows people to concentrate urine because of lack of adh

37

potassium sparing diuretics

• Function in the collecting tubules (ducts) to
prevent Na⁺ reabsorption and K⁺ excretion. Antagonize aldosterone

38

mineralocorticoids(aldosterone) is produced

in glomerulosa

39

zona fasciculata

glucocorticoids
(cortisol)

40

Zona reticularis

androgens
(testosterone precursors)

41

Potassium-Sparing Diuretics
• Used to treat HTN, often in combination
with

thiazides. not efficacious by themselves

42

potassium sparing are problematic in

patients with hyperkalemia
(like who?) like patients on bypass or renal failure

43

Potassium-Sparing Diuretics
Direct Aldosterone Antagonists

Resemble sex steroids chemically. Used as adjunctive therapy in heart failure
– Statistically decreases mortality and helps
prevent pathological “remodeling” of the heart

44

diuretic of choice for
liver failure patients with edema

*Spironolactone

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Potassium-Sparing Diuretics
Direct Aldosterone Antagonists
***Ineffective when

used on patients with Addison’s Disease because they have hypo adrenal function. not producing aldosterone. so giving this drug will have no effect

46

Potassium-Sparing Diuretics
Indirect-Acting Aldosterone Antagonists

*Block the Na⁺ transport channels affected by
aldosterone rather than aldosterone itself.
-VERY similar to direct aldosterone
antagonists except they can be used in
Addison’s Disease patients (why?)

47

5: Osmotic Diuretics

Small non-metabolized molecules filtered
through the glomerulus that osmotically
carry water with them. Given parenterally as they cause severe
diarrhea if given orally (why?) good for renal patients
• Mannitol very commonly given on bypass
or added to the prime solution
• Urea and glucose rarely
(if ever) used (so feel free to ignore)

48

Osmotic Diuretics works

Work in the proximal tubule and the
descending Loop of Henle which permit the
free passage of H₂O

49

Osmotic Diuretics
Perfusion Relevance

Commonly used to “draw” fluid into the
intravascular space and decrease interstitial
edema but…why might this be controversial? because it increases hct.

50

Osmotic diuretics used to maintain flow

for renal failure. prevents accumulation of crap in kidneys. also good for cerebral edema. good for patients who smash their head

51

Osmotic Diuretics -Problematic in patients

oliguric(little urine)/anuric (no urine)
renal failure (why?) will go into urine and pull fluid and cause htn.

52

dont give mannitol when urine output is less than

<50ml/hour for three
hours after a 12.5 gram IV dose, AVOID.

53

Mannitol is excreted (not metabolized) within

one hour, so repeat doses can be given.
-MUST be given slow IV or profound transient
hypotension will occur due to skeletal muscle
vasodilation
“And I will be quite
ANNOYED. crank up flow it will wear off

54

Mannitol (Osmitrol) is a small molecule

categorized as a “sugar alcohol” With its familiar cousins xylitol and sorbitol.

55

Mannitol is usually supplied

as a 20% solution.
*What does this mean??! 20g per 100 ml
• RULE #1 when giving mannitol:
“Check the bag/bottle
for precipitated
crystals!!!!

56

Check the mannitol bag/bottle
for precipitated
crystals!!!! because

beacause it will concentrate in the crystalsand you wont be giving as much plus its crystals dummy